I'm on my 3rd child and I've had mild cramps here and there but nothing severe. I wouldn't worry too much about it unless you start having some type of unusual discharge (blood or gray) take an aspirin for the pain. If you're really worried go into a walk in clinic ASAP.
None of my Drs. let me have aspirin, so ask yours first. I dont know if your pain is like crambs, usually are normal but is true that you should be aware of discharges and don't worry too much. I had the same in one of my pregnancy and everything went fine. Remember each pregnancy is different even for the same women.
I am 9 weeks and I also would feel cramps at night from week 6 to now. I had my ultrasound and the baby was fine. Someone told me that I might be dehydrated. I tried drinking water when it happened and they went away. Now I really try to drink a lot of water and I keep a bottle on my nightstand table just in case ot happens during the night.