SO dog just

So my boyfriends dog just ran up to me and acted like a dumbass and hit my stomach with his head and paws.
I almost fell back , not enough to fall on the floor but enough where i wasn't ready for him to do that and i had to catch myself before i did fall. 
Now my stomach hurts . Its kind of crampy like feeling. I'm really scared . My SO almost hit his dog because he did that . He was devastated and shocked , and i am too. I don't know if its nerves, me being worried or what but i feel uncomfortable now . My stomach is in pain. I cant really walk because when i do it feels like period like cramps to the point where your hunched over and in pain but its not that severe . I'm worried . what should i do?