I also agree, see a doctor. I'm very concerned about WHY he would punch you in the stomach. Is he abusive at all? My dad did similar things to me growing up, and I had massive amounts of bleeding from it - in various places I probably shouldn't have bled from like I did. If he IS abusive, you need to talk to someone desperately badly and get away from him.
In terms of your questions, it would only be pregnancy if you were sexually active. Based on your profile age you're only 14. I'm hoping that you're not, only because you're incredibly young. It could be your cycle being off and strange, but it's so difficult to say. Especially in your current position.
Yes, Please go to the doctor right away! I know that you probly want an answer, but this could be a number of things, including and emergency situation. Its definatly not good and really needs to be seen by a doctor asap. i hope everything is ok, God bless :)
How hard did he hit you?!!!!! There is any number of possibilities. You need to go to a doctor and get checked to make sure there is no serious damage and see why you are bleeding if it is not time for your period. I hope you are ok, Best wishes to you.
Sissie