I Have Have Stomach Pain Since Around 12 Noon Today.

I have have stomach pain since around 12 noon today. This is around my belly button area and I feel very swollen. There is real tenderness in the center, above the belly button. At first I thought it was probably gas but the longer it goes, and how painful and tender it is (I actually feel a lump above the belly button), I'm beginning to get a little nervous. I have no fever but do have periods of nauseousness. Should I be concerned?