I suggest you look up former posts on sore feet/sore hells because a lot of us suffer from this pain and have written about it. I had it for ten years and the only thing that's helped more than short term (yes, I did all the shoes, inserts, gels, treatments etc) has been to get the overall inflammation under control. Classic PF actually passes usually within two years but really, it doesn't matter what we call it (enthesitis is the more usual diagnosis of this pain for AS patients), the point is, it's because of inflammation. I am slim, never overweight and was followed up to diagnosis by a very good Rheumy who noticed that one heel was "fatter" ie. More inflamed, than the other...

It could be Morton's Neuroma causing the toe pain.  I've had that with the PF.  My podiatrist gave me a series of cortisone injections to help it clear up.  The PF has never gone completely away.  The Humira, though, has helped with both!

I have been dealing with feet problems now for about 5 months.  Could barely walk for a few days.  Went to Rheumy then to Podiatrist.  They keep telling me Plantar Fasciitis, even gave injections to bottom of my feet, shoe inserts, and a stretching boot.  None of this seems to help.  I have had PF before and when I would do stretches, I could feel the tightness in my feet and calves.  No tightness this time.  Rheumy recommended MBT shoes to take pressure off front pad and heel of my feet.  That has really seemed to help.  Podiatrist recommended New Balance shoes for volleyball because MBT's are kinda hard to play in.  I don't think it is always normal PF.  I think AS patients have inflamation in the feet that is not exactly PF, but no one knows what else to call it.  Rheumy recommended using a TENS unit on my feet.  I am going to try that next.  Best thing is stay off your feet as much as possible and use ice.  A frozen water bottle works good.  Hopefully, this will pass.  AS problems seem to move around.  Waiting for it to move elsewhere!

I have the same thing.  Rheumy told me it's plantar fasciitis and achilles tendonitis.  I also have a thickening of my achilles tendon from the inflammation.  This pain started for me when I was 120 lbs (before i had my son lol) and excercising twice a day and working a full-time job.  Being a healthy weight and active doesn't prevent it, it's from the inflammation as everyone else said.  You should talk to your rheumatologist and see a PT to get some good stretching excercises.  I have to stretch everyday or the pain gets worse and can hardly move my feet.  If I don't stretch my achilles tendon I can barely put my feet flat on the floor and can feel the pain where it attaches in my calf.  Good luck! Hope you feel better!

I have begun having the same pain. I wasn't sure what it was. The pain in the bottom of my feet has become increasinly worse. I also have pain in the bottom of my big toes. It feels almost like a needle poking in it. Do you get pain in your toes as well?

Same thing I've bee dealing with for a while now.  Even when I used to stand up the throbbing pain was almost too much to bare.  It doesn't help that I stand all day at my job and I've been going to school for a few years for firefighting.  But the pain became so bad that some days I could barely walk.  I would even set aside almost an entire day every week to just stay in bed, rest and ice/heat my feet.  It was very frustrating because no one really understood the disease correctly.  I went from an orthopedist to the foot specialist, back to another ortho, then back to the foot specialist.  Got all kinds of advise, orthotics, Celebrex, and bunch of other stuff that never helped.  When I finally met a good ortho that semi-diagnosed me I got some decent treatment from a rheumi, but the infamation had gotten so bad in my toes, arches and heels they where permanently disfigured slightly.  Take it from me that if it hasn't gotten better in weeks, be your own advocate to your health.  If something is not working for you, try to move on so that you can get closer to being better.  I had doctors, friends and family tell me everything from gout, riters disease, tendinitis, bone spurs, fractured ankle, etc.  And as far as your pain goes it was the same with me.  First my Achilles hurt on and off, but then it hurt for an entire year.  Then my feet started hurting on and off, then after a while they hurt everyday and the pain got worse and worse.  I went through three pairs of different work shoes, four pairs of inserts and having to crawl to the bathroom at night before I realized that it was something more than regular work related foot pain.

I have the same issue.  Also not overweight. I keep under control by wearing good shoes.  Never ever completely flat shoes.
Barefoot walking can make it worse too.
Try a no impact exercise on alternating days. You shouldn't be running.
Walk one day. Swim or bike the next, give your feet a break.  
The worst thing for me is definitely flat shoes, Like flip flops or flat sneakers.

The physical therapist had me start wearing different shoes to protect my feet more, and that alone was worth the money I paid to see her, and I don't have PF now.  She said that if your feet take less abuse with every step, it helps prevent the pain and PF.

It sounds like plantar faschitis. I have had it for 3 years along with Achilles tendonitis(back of heel). My reumy say it's because of the AS.It's caused by inflammation. It comes and goes with me. Sometimes it's so bad I can barely walk. I have went through pt treatments twice. Doesn't seem to help me. I have developed bone spurs now because of the chronic inflammation.Pain is always worse when going through a flare up.Here are some thing that have helped me. I wear orthopedics in both shoes and my podiatrist gave me something to stick to the bottom of my orthodict to give a slight lift. (this helped immensly with the achilles),Massage in the calves because it's all connected to your feet.Stretching out calves and the feet.And last but not least ice for 10-15  minutes. Doing all this together does work. In my case it's never fully gone away but I do have days here and there with no pain or very little. Give it a try it works! Good shoes are a must! ~Bless you

Yep sounds like PF.  I had it bad in both feet 2 years ago.  The rhuemy said it was from having AS not from being overweight.  I had x rays and a MRI to confirm.  Then I chose to use PT to heal it.  It was so painful but after about 2 months of PT it got better and has totally gone away.  The therapist did make me cut down on my exercise down on my feet until treatment was done.

Since you're not over-weight, you probably don't have enough of a fatty pad on your heels. Either way, the treatment is the same - stretching and good shoes. Keep treating the systematic (body-wide) inflammation. The only thing you should add is rest. Don't do anything that will aggravate your heels more. No impact exercise.

Sounds like plantar faschitis to me. You dont have to be fat or out of shape to have it...it is caused by inflammation. It is very painful so make sure your rheumatologist knows what is going on! I hope you feel better!