When i do push-ups a part of my stomach hurts...?

When i do pushups, like 3 inches left from my belly on is where it gets painfull..i know it hurts because im like a flat board when i do pushup, and im completly stretched out, but idk if its just cause its really right or my muscle just needs stretched out, but it JUST started happening, and i never had the problems before, why would this happen suddenly?