I didn't know whether to laugh or scream when I read your post. Fourteen year old boys can be so exasperating, can't they? They have no past and no future, only right now, and if they don't hurt right now, then everything is okay.
It sounds as if he undoubtedly had arthritis. Whether the LSD or time made him better remains to be seen. After a few days of starch, he and you may have an answer.
Meanwhile, my heart goes out to you as you try to deal with a teenager who seems to have a chronic disease. Teenagers are rarely easy and one with health problems presents special challenges.
I wish you the best in dealing with him!
Karen