The back of the arm could be players elbow. Sounds like you have more than that. Have you ever done trigger point therapy on yourself. It could help tremendously. I've literally felt relief rushing down my arm before when I couldn't even hold a pencil. Check out the book The Trigger Point Therapy Workbook, but Clair Davies. It's so good I literally have the 2nd and 3rd editions.I have a similar issue right now. If I flex my biceps (like double biceps pose) I get strong pain near the point of the elbow and the back of the arm where the triceps connect to the elbow. Also pain in the joint when curling (I can do triceps pushdowns for example with no problem).
Biceps Tendonitis?