Has anyone taken Prometrium?

I am on 100 mg. daily now for 17 days- the Dr. wants me on it for 21 days and then off for one week. I felt like I was going to get a period a week ago, I was crampy and bloated, but nothing happened. Also I am really bloated now and feel tired a lot? I think I have gained some weight on it. Could those be side effects of the prometruim?

Please share you experiences with it as I am deciding if I shoud get off it or not.