I went to my sports medicine doctor today to help me with a problem I've been having with my elbow for about 6 months.
After examining me he proclaimed I had classic tennis elbow symptoms. So I was explaining the situation where it would have come up, so that he could suggest a way to continue without further damaging the joint and we decided it was caused by my drywalling work.
Picking up sheets of drywall by the edge with one hand to lift them into position, oddly enough he's seen cases where using a screwgun aggrevates it, painting overhead, using a hammer incorrectly (using wrist action to pound the nail, not my arm). So he suggested I start wearing a tennis elbow strap and begin icing my elbow after doing any more DIY jobs. A couple 3 months and I should be back in fighting form.
In retrospect I should have known unloading drywall by myself from my truck would injure something, but I always wrote it off as a muscle pull (which it is) but not something so extensive.