Penile pain. She isn't sleeping around.

I have been having pain in the tip of my penis, It has been hurting all day and has been going on for about two days now and I am not sure what the problem is but when I go to urinate it stung a little day one but was bareable but now when I go to urinate it burns so bad... it gets worse and here's the embarrassing part why I don't wanna go and see a doctor in person if I can stay away from that.. but if I squeeze my penis anytime of the day a white like discharge comes out and it's too milky or creamy to be semen but it is sticky like semen but anytime I squeeze the tip of my penis the hole fills with a little bit of this white substance and it's just weird and I don't have any extra sexual partners I have been sleeping with the same girl for 3 years now but online the only thing that comes up as pain in the penis, burning while urinating, and white discharge from the penis is a STD but I have no idea how that could be if I have the same sexual partner and she isn't sleeping around..