I have been feeling a light sting on the tip of my penis everytime im done peeing, it does not hurt or burn when i pee i just feel the light sting after i pee right on the tip around the head area. Also when i am sitting or standing i feel like i am still dripping pee something out but nothing is there and i feel the sting very very lightly. It's been going on for a week now and i am starting to get really worried and scared. I am not sure to think of it as some type of std or uti. My last sex partner just tested negative for everything. Any help or advice?