So, you're about to pick up the old guitar and write the next great song.
It's bad enough that your dog ran away, your truck is busted, and your significant other is cheating, but now your hands and arms hurt. It's most likely that you have tendonitis.
What is it? An inflammatory condition of a tendon caused by tearing and abrasions due to overwork under conditions of high muscle stress. Read - too many all day sessions.