If that is your biggest worry, I'd see a doctor and get yourself thoroughly checked out. And abstain from sex until you do so that you *don't have to* take birth control. It's not hard to abstain.
Tell the receptionist your symptoms and say that you need to see someone as soon as possible. Call as many doctors as you can and get yourself an appointment with *somebody*.
I doubt you are pregnant, but your symptoms could indicate a hormonal problem. That would also affect your periods. Get checked out.