I had similar pain on gonal-f. After the hcg shot, I swelled up so bad that I couldn't sit down at all! It was hell to have to drive (in rush hour traffic no less) an hour to go to the dr's to confirm that it was not hyperstimulation. Just that I had about 12 follies that weren't big enough to get released that were still growing as a result of the residual meds in my system. He said that my ovaries were about 10 times their normal size and the pain (and bloating, I was wearing dh's jeans because mine were excruciating) was just them all trying to fit in the little space. The pain subsided a bit about 2 days before af arrived. I was on bed rest for 6 days because I could not sit long enough to drive into work (I live an hour away) I spent most of my time standing up or lying down. Thankfully, there was nothing seriously wrong with me. They told me I could take Tylenol for the pain, but it didn't really do much for me.
I hope that helps. I also hope that there's nothing wrong, that it's just everything stretching and growing!