Why is this happening?

Over the past week, I have had stomach pains frequently, especially when standing up after prolonged periods of sitting. It isnt severe pain, but it is unusual. I have also been farting a lot more than I usually do. Every now and then I feel a small sharp pain in the same spot in my stomach that hurts. Why is this happening? I have no known allergies (such as lactose intolerance) or anything of the sort.