It could be everything stretching inside, making more room for baby, and getting you ready. I remember with my first born around my 30 week mark a lot of stretching and pain. Your body is going through a lot right now. It sounds normal. But if you're concerned about it, maybe call your doctor and ask. I know you can hear all the opinions you want on here, but something about the word of your doctor or a medical personnel is always more reassuring. Hang in there momma. You're doing amazing.