Hi, Maureen:
Costochondritis is ribcage pain and very common in AS. I had it to the max until about a year on NSD and antibiotics. It usually has a bias to one side; most AS pains are asymmetrical, unlike RA and FM.
This pain can be miserable, and I remember just a slight touch on my sternum caused very shap pain, eventually just breathing hurt.
Good luck with it,
John
"On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?"
Charles Babbage