What does it mean when your penis leaks fluid?

I am only 16 years old, and for the past 2-3 days my penis has had a stinging of some sort as if i was just trying to push a piss but it occurs only when i touch it really or move around, its not at the base of the penis like the head or anything its more like inside where piss comes out, possible explainations are that i had unprotected sex with someone recently but that person assured me they have been checked out recently and are clean, other explainations i thought of are soap/chlorine mixes since its summer, and the final possibility is that when i masturbate i seem to not be able to get aroused or ejaculate unless i have pressure on my penis like if you take your penis and like push down to stretch it to its furthest and jack like pushing on the bladder almost which i heard was bad from a Louis CK comedy special if thats what he was referring to. please help me ive been checked for STD's not too long ago n all came back negative so i dont think thats the case because ive been having sex with the same girls since then and havent had a problem til now, and if this means anything i smoke cigs, ganja, and drink at my age n have been since like age 11