I have a terrible pain In my stomach!?

It' In the middle and not on the side the pain starts from the top of my stomach to the end. It feels like that pain you get on your side when you run sometimes. I woke up with it and I can't do anything I can't stand I can't sit it's really painfull to lay down and I can't take deep breaths. It waves from really strong pain to mild pain. I don't know what to do what could it be!?