Cramps a week after sex

My SO and I had sex a week ago today. As soon as we were done, I began experiencing some EXTREME cramping that felt like a knife stabbing me in my lower abdomen, legs and back. While it isnt particularly abnormal for me to feel some sharp pains after sex, this time it was really bad. Like I couldn't stop crying and him asking if he should call 911 bad. The stabbing pain was still there the next day and I got a fever and chills and was in bed all day. The pain lasted three days and then all of a sudden I got my period, which was 4 days early (I'm usually late). Now I normally have severe period cramps, but these usually start the day of my period, not before. I noticed today (day 4) that I have some cramps again. Has anyone experienced anything like this? I know some will say go to the doctor and I'm all for that if this continues, but just wanted to see what others had to say about it.