Talk to your doctor, have him/her write a letter you need to rest and can't over work, I had the same thing and I work in a medical field. They even counted the times I used the restroom which was horrible because I'm pregnant and baby kicks bladder which makes you pee a lot. Some people think being pregnant is super easy and that they are all the same
If your just tired... you can have the strength to do it. Soon you cant work at all. I know its hard but you can do it.
Let them count your restroom breaks, as long as they dont write u up for peeing. And if they do it can turn into a lawsuit.