UTI/Kidney infection. Help or advice?

In the last 6 weeks I've been suffering from uti symptoms. It burns when I urinate, I constantly feel the need to go to the bathroom and overall its just very uncomfortable. It would die down for a few days and then flare up again. I began to start vomiting one night and broke out in sweats so I decided to go to the doctor and got prescribed antibiotics. It cleared up after a few days. A week later I had sex with my boyfriend and now I'm back to square one again. I've been having regular sex with my boyfriend for almost a year now but its only recently ive been showing these symptoms. I'm doing all the usual, drinking lots of water/cranberry juice and peeing after sex but nothing seems to help. I'm just wondering is there any other preventive measure I can take to stop this from reoccuring cause its really really uncomfortable. I dont want to keep taking antibiotics either because I'm prone to bad yeast infections and thats nearly as bad as the uti symptoms. Any help or advice ?