Sorry about your sons diagnosis.

Keep that young man as active as you can. Execise I found to be the best defender from AS.
I was diagnosed with AS about 2 1/2 months ago. I'm 31, I look back and I know I,ve had it from about the time I was 19.
My symtoms started with sciatic nerve pain then acute upper back pain to constant lower back pain and stiffness, constant dull pain all over. If I got bumped to hard my muscles in my side would cramp and it fealt like my bones were ready to break.

and now its my left hip. starting in my left knee.

I have had that same with preesure in my chest.
It feels like its my heart. Its like I get pressure right over my heart and Im unable to take a deep breath. Its not painful until I try to breathe deep. It almost always last about a minute. This has probly happend to me 50 times in the last 10 years. I too have had some test done because I was freeked out from it. The docs were unable to find anything. My opinion is the issue Im getting in my chest is my rib and muscle in that spot. Its an isolated spot about the side of a thumb. I think it may be cramping in that spot just like i get cramping in my side ribbs, my back. Acute cramping unlike cramping in your side when you run. I tend to get these cramps right before I get a flare up.

I can say once I started taking 20 mg of bextra a day, 95 percent of my AS symtoms are gone. Ive been on it for about 4 months.

A friend recently told me about how he once had heart pulpitations.FAst slow stop fast He said he suffered from that on a regular basis. His docs found nothing wrong with his heart. He said he talked to a dietrician and was told his body lacked potasium and that was the cause. He said he now takes potasium supplements daily and no longer has heart pulpitations. He said he stopped taking the potasium at one time to see if that was really the cause of them ceasing and they came back very quickly. So he went back on the potsasium and the pulpitations once again left.

blessings to you and your son. smile