Yeah, that's what I thought, although a fracture seemed unlikely because there was no swelling. Interestingly, the ulnar process does appear to be slightly more prominent than I'd remembered it (and more than the one on my right hand), but that may just be because I'm more conscious of it now.
I noticed in training last night that this injury has really affected my self-confidence--I'm a lot more hesitant than I've been in years and it's affecting my ability to do unrelated techniques. Just one more step along the tortured path to developing "no mind."
I think I've found the number for the doc that Jack suggested--will be calling him today to see if he knows anything about this type of injury.
Thanks for your help!