I just wanted to share my current situation, and see if anyone has gone through something similar and can offer advice. If I play longer than 30 min or so, I get the worse pain in the thumb on my fretting hand. It's not necessarily a shooting pain, but similar to the tendonitis I had in my knees during high school football many moons ago. The pain does not go away until two or three days later, even if I do not play at all. I plan on going to a doctor to check this out, but I need to get insurance first, and that might be a few months. Here are some of my ideas: 1. Improper technique- (and why I posted in this forum) Although, I am mostly self taught, I have taken about a years worth of lessons over the past 16 years. None of my 4 teachers said anything about improper technique on my fretting hand, but I won't exclude it. My thumb pretty much stays in the middle of the neck, on the tip, and the angle between the thumb and the neck is a 90 deg angle. (Like trying to push your thumb through the neck instead of holding it like a sandwich) I noticed the pain came a lot faster on my Geddy Jazz as opposed to my Stingray. The thin neck has something to do with it I suspect. 2. I severly dislocated this thumb (both actually) playing some full contact basketball in middle school. I wore a splint on it during wrestling 3 weeks after it happened, and was fine. I started playing bass a year later, and the thumb never hurt in the last 16 years of playing. This makes me believe the injury isn't a factor, but again could be wrong. 3. I just turned 30, and came off of a year break in which I rarely touched my bass. I think 30 is too young for arthritis, but maybe not. From what I read on arthritis, it is an immune system thing, and usually doesn't form in only one joint in the body. It might be possible that I started playing too much right away, and my hand just can't take the punishment yet. However, I have been playing again for about 4 months now, and I still have the problem. Any ideas? I am actually really scared that I will need to stop playing for good, and learn another instrument. The pain is bad enough that I only play a few times a week now, and need asprin afterwords.