I've experienced severe ibs symptoms since the insertion of my mirena (levonorgestrel) iud (gas pain = the worst pain i've had!) how would an iud affect gi issues?

Consider going to ER: Since it is the worst pain you have ever had you should go to the er. The worst case is a perforation which can be a surgical emergency or an infection.

IUD and abdominal Pa: Dear amelia, the most important thing you must do is have your gynecologist assess the status of the iud, has it slipped out of position, is there an infection , is there some allergic reaction. Abdominal pain like ibs can be indecipherable from pain emanating from your female organs.