IUI with severe cramping

Did 1st IUI after 6 days of Brevelle w/4 follicles at mature levels. I m sensitive to medicines - can

[Lea2001]

I had a similar experience, but I was only on Clomid.   I had sever pain in the abdomen and across my back near my rectum (sorry tmi).   I thought my ovaries were overstimluated because the doc did not do an ultrasound to check.   My doctor had to leave right after the procedure and the nurse saw the pain I was in, but she was no help.  
The next month, I was OK.   No pregnancy, but when I did go to a specialist, she did a full internal exam and ultrasound and there was no problem.   I had a surgery about 5 months after the painful IUI and they found endometriosis.   Maybe that cause the pain.
I really don't have an answer... but I had the same experience.