Chronic UTI

I have been getting UTI's almost no-monthly for over a year.  I have an IUD.  My GYN feels certain that the IUD is not to blame.  I am being put on low dose antibiotics to take after sex to try to ward off the infections.  Anyone else have this type of experience?  Anything work?  I shower religiously, pee before and after sex and have been with the same guy for 10 years.