Recurring UTI?

I have an IUD, and since I’ve gotten the IUD I get a UTI every month or so, after sex. (July, August, September, November, December, and now) I always pee right after sex!! This is so irritating, it’s gotten to the point that my doctor will just order my prescription as soon as I call in and say “I have ANOTHER UTI”. What should I do to stop this???