Can you help me? Please read! Possible tmi

This is my first pregnancy and my son just came running with his hands out from the other side of the room and pushed right into my stomach. He is 4 years old with adhd and we've tried to explain to him not to do this over and over and he still does it. This time he hit and it made me instantly nauseous and sick, with cramping, should I go to the doctor? There is no blood