I'm totally butting in here but on the fists can do nasty things to your alignment. Find a teacher to talk you through half-dog. Half-dog will help your body make the changes it needs to make so that down dog won't bother your wrists any longer.

In terms of disrupting the class, I used to have a friend with the most gorgeous long hair and in the course of an hour and a half class, she would move that ponytail at least a dozen times to accommodate different poses. Most students won't even notice. Unless you are stinky or talking, most things aren't as distracting as your own mind is making them out to be.