Go to a Physical Therapist!! Just get a general referral, and let them evaluate you! You likely have a lot of tightness/issues that you aren't even aware of. The injections usually don't help because it's not as simple as just numbing pain in one very localized area. If your pain is (and I say IF) musculoskeletal in nature, it likely is the entire thoracic muscles/tissues that are affected (some more than others). The therapist can help localize the sources of your problems and help your loosen tightened areas and teach you ways to help maintain that on your own.

I think anyone who has had GI issues for a long time, likely has tightness/tension in abdominal wall, even back muscles, because we tend to 'hold' areas of pain tightly.

See another thread on here that just started about MFR, myofascial release,one technique used by therapists.

Most MD's don't understand or have any clue what PT does. I'm surprised you were diagnosed with a musculoskeletal problem and NOT sent to PT! Ask your doctor for a referral, if he/she won't give you one (I can't imagine they wouldn't), maybe you have a primary care or other doctor who would.

It can't hurt, you will learn a lot of things that are helpful, and if it doesn't help at all, will rule out having a musculoskeletal cause for your pain.