I am 34 weeks and have been getting menstrual like cramps around 31 weeks. At 32 weeks they were so bad at one point I called my OB because they were coming quite frequently. I sat down and drank some water and they only came again every now and then. They told me it was just Braxton Hix and nothing to worry about unless they became regular and/or more than four in an hour after I got off my feet. Does your whole belly tighten up when it happens? I would try to lay down on your right side and drink a cold glass of water. It still happens sometimes but not regularly. Try to call your OB for reassurance if you are not sure. Good luck and I hope you start to feel better soon.
Cramps can be from the uterus stretching. As long as there is no bleeding, you are probably fine.
It depends on how bad the cramps are. Every pregnant woman have them at some point. When you notice them, try lying down, and resting. Paracetamol is good for pain relief. If it gets serious, and or unbearable, call your dr, just to be safe. All the best. :) xx