Diagnosis?

Back from the doctor. He seems to think the problem is most likely costochondritis (which is basically inflammation of the cartilage connecting the ribs to the sternum. He also thinks there may be two or three detached ribs.
The course of action for now is to stay on the medication I'm on for another two weeks. After that, we'll try a different pain med if I'm still in pain. If things haven't improved by the middle of June, we'll do a CT scan. If it turns out that it is costochondritis, they're going to try a temporary nerve block. If that works, they're going to go with a permanent nerve block, killing the nerves that are causing the problem. If that doesn't work...well, who knows...