Stomach pain from pants

Okay so i wear pants that are comfortable for me at least they used to be before pregnancy. I don’t remember this happening with the last pregnancy until almost 10 weeks and it was only when I sat and it was just uncomfortable. I would just unbutton and be good. Now it’s super painful and will give me cramps for hours I literally have a hair tie around my pants just to keep them from looking weird unbutton. The wierdest part I am only 7wks going on 8 in 2 days. And I have actually lost a pound my belly is bloated but nothing insane. What is going on with me. Even some of my underwear is now doing this and I am about to go buy new pants ugh