Red Footed Tortoise has small white bugs in cage

by olds
(michigan)

We have a red footed tortoise and have noticed that there are small white bugs in his cage. I have changed the bedding and we do often but am wondering what these bugs are and where they come from? Is there a prevention for this?

Also I have heard that once a tortoise flips over onto his back in which ours does every now and then that they cannot breathe, is this true?