I've only had one IUI and I did have cramping for 2 days afterwards. I agree with the above, if it persists or seems to worsen I would call the RE office. Good luck to you!
A few days after one of my tries of IUI I did have cramping, sort of felt like period cramps. I have read where other women felt the same thing. I have had 3 IUIs at this point and only one gave me mild cramps.
If the pain becomes concerning to you, you may want to a call your RE/OB and at least talk to a nurse.