Hi, Maybe Once Every Two Weeks I Get A Uti

hi, maybe once every two weeks I get a uti from having sex its get to the point where I cant even pee but I feel like im busting. its doesn't take long after sex. it usually start happening 5 hours after and its doesn't start stinging it goes straight to the feeling where im busting to pee but cant, why is this happening so frequency & the only thing that stops it is anitbiotics but I cant keep having them every couple weeks.