I have had 3 yeast infections in 2 months, or so I thought they were yeast infections. There is a yellowish, rancid discharge. I recently got an IUD inserted and I'm wondering if that has anything to do with it. Please help I don't know what to do and this smell makes me sick.

That is a sign of a very bad infection and you should go to your doctor as soon as possible and have it taken care of. I don't know if the IUD is the reason.