Welcome to the Healing Well site, Chronic Pain Forum. Glad you posted your question.
I, too, thought of Chostochondritis when I first read your post. But I'm also glad you had thorough check ups. You must rule out problems of a cardiovascular nature when you are feeling chest pain.
Anyway, NSAIDS, such as Motrin, and Naproxen work well usually with this issue. You might try one of these, if you can tolerate this kind of medicine. Also, please know that your doctor can prescribe other NSAIDS (non-steroidal anti-inflammatory drugs) in higher doses if he feels it will help you.
Please come back and let us know how you are doing. I have had Chostochondritis before and it was very painful at times. One time, I remember, I had to pull my car overto the side of the road and stop driving because the pain was so disturbing.
Anyway, I hope you find answers to this perplexing issue.