Dealing with Chronic UTIs After Sex

I also get UTIs after sex. I have tried everything from taking DMannose and cranberry supplements, drinking a ton of water and always go to the bathroom after sex. I can go 9 months without one but once I get one, they seem to come in a series of 2-3 back to back. A few times I had blood in my urine. I take nitrofurantoin and it usually helps immediately unless I have a more severe case and then it takes longer to be symptom free. Any other suggestions?

I've dealt with this and it's the worst. I got prescribed macrobid. I take one after sex and I haven't had one since.