So after playing for a solid year now, I've noticed that I get extreme fatigue (read: discomfort bordering pain, like a muscle or joint being overused) in the bottom joint of my fretting hand's thumb. It's not really dependent on how long I play for (sometimes it's there within 5 minutes, others, half an hour) but when it comes, it's usually there until I give bass a break. Sometimes I can alleviate it by fretting a little lighter, but obviously at the cost of notes going dead, or buzzing, or any other unpleasant sound associated with not committing to a fret. My question is: Is this something that will go away with time, as in, I'll get used to it, or is it indicative of a problem with my overall fretting technique? Back when I started bass, I was instructed to generally keep my thumb congruent to my middle finger, but is this advice good or bad?