Much great advice has been given already, but id like to share these two videos which helped me get past similar issues to what you are having. One thing I would say however, is get another teacher...
That second video is the one I always go to for left-hand technique. Everybody's body is a little different, and you may have differences in terms of strap height and the angle the bass hangs at, things like that. But it should come together in a configuration where your left hand position is natural and relaxed, your fingers can move freely and your wrist is more or less straight.
I thank every for their responses. I figured there would be some discomfort, but I'm experiencing pain in the sense where it feels as though the outside portion of my wrist is about to break. I'm still in pain today, which sucks, because I have a job where I type all day.
YIKES. As others have said - pain is bad. Don't try to keep going in pain and think it's going to get better. That's your body telling you something is wrong. If your teacher doesn't get that, get another teacher.

