I had IUI on Sunday and Monday and the day after the trigger I had really bad O pIn on the right like never before!! I could barely walk too! It was my 2nd cycle on Femara and Gonal F and this time had 3 mature follies so perhaps why it was more painful? The pain lasted about 5 hours or so.
Now, I've had a couple of instances of right O type twinge very mild (I don't usually get that). However I'm also on prometrium so who knows.
My RE says that the fluid released is an irritant. And if you have that many follies, you will feel it more intense. I have had it as bad as you say, where you feel like you are being cut in half :) It will go away. Good luck.