I'm 25 years old, healthy and fit but 2 years ago I've had unprotected Se× with a unknown married women since then till I'm having always burning sensation inside the penis, I'm drinking 5 L of water per day, urination is clear but after urination again burning start, I've consulted many urology dermatologist but didn't get cured, I've checked the std also like hiv hep b, hep c, vdrl, what it could be, is gonorrhoea or chlamydia because I haven't checked those sti yet, please suggest me what to do, what type of std could cause burning sensation inside penis.