Severe Abdominal Pain, Dizziness, and Nausea After Sex

Immediately after my boyfriend and I had sex last night, I started experiencing the worst cramps I've ever had in my life. I also was so dizzy I couldn't walk, my vision blurred and had black spots, and I felt very nauseous. I felt like I was going to pass out but I managed to fight it off. I couldn't form complete sentences, and it was very difficult to speak or move. I put a cold rag on my forehead and most of my symptoms went away after 30 minutes, although I've had cramps most of today, but just like normal period cramps.