The frequent urination thing really depends on your age. The older you are, the more likely it is to be a result of something like prostatitis, BPH, etc. It could also be a sign of diabetes. Could be anxiety, but I'd get it checked out.
The erection difficulty also depends on age. The older you are, the more likely you are to have difficulty getting rock-hard erections. Another age-related issue: if you used to wake with erections and don't anymore, you should see your doctor, because ED can be an early sign of circulatory problems. But if you're young, chances are it's just due to anxiety/stress.
frequent and urgent urination are classic signs of a urinary tract infection.
i dont think it has something to do with HIV
I dont think they are related to STD but the things you are taken. Even protected sex and I still feel paranoid about catching hiv. Use a rubber and stop playing russian roulette, you might end up getting hit.