Water water water! I hardly pay attention to the amount of water in drink (or lack of) and I've noticed when I get dehydrated (very easily) I get cramps to the point of doubling over in pure pain. Try drinking water as much as possible (I chew ice all day)
Im on week 31 and get the same symptoms i noticed drinking water and stretching helps alot. If not i take a nice "warm" shower (NOT hot) and it seems to relieve the pain. But they do say menstrual cramps are a sign of labor contractions but my doctor said if its not consistant its most likely false contractions or your bodies way of preparing its self for labor.
Did you end up going to the hospital?
Try drinking water and putting your feet up if it doesnt go away then you can go in to check