Usually for me it is a dull pain low in my belly, but there were a couple of times earlier in my pg that I felt some sharper pains - I think they were wind pains.
I know that pregnancy can have this effect on us, but it really is possible to combat it with fluids and fibre - you don't have to suffer! I find that if I have something cereal-ly in the morning (porridge is a goodie) and a salad element to lunch, and drink a couple of bottles of water each day, I'm running like a train without any probs. Hopefully you can overcome your tummy pains and get on with enjoying your pregnancy. xx