I think you have to start with:
How long have you been playing? and
Do you play almost daily, or are you a weekend warrior?
If you have been playing for years, and you play regularly, then return to the previous post.

But, if you are a new or infrequent player:
Stamina rears it's head for bass players. There Is a physical part to bass playing, and, like an athlete, you need to build stamina. When I was first learning to play, I had pain frequently, but it wore away as my fingers/hands/wrists got stretched out and stronger.
Interesting that this thread came up, because, I am now experiencing pain after starting to work on Rocco muting technique. It's forcing my hand into a different kind of position, and it actually hurts me after a while. But, going slow, steady, and regularly, I'm expecting it to work itself away like the past.