Redness on my penis ever since unprotected sex. Smelly urine and overactive bladder.

So, around a year ago I had unprotected sex with a girl I met at a club. A few days after, I noticed that my glans were red around the bottom and my urine started to smell. Ever since, I've had smelly urine an overactive bladder and redness on my glans. I've noticed that drinking alcohol makes the problem 10 times worse. After a night out of drinking cider, I always come back to smellier urine and much worse redness. 

I started to think that the problem was yeast related, so I ordered some flucazole, which was one 500mg tablet. I even tried doxycycline and another antibiotic which was used to treat urethritis. Whilst the urethritis medication eased my bladder, I still had redness around my glans and my bladder was still overactive. 

Often my penis gets itchy and when I go to a sauna, my redness gets much worse. I'm hoping its yeast related and am starting a VERY low carb diet as of today. It not so much the redness that's bothering me, it's the overactive bladder. Whenever I go out on a night out and drink alcohol, I'm constantly back and forth to the toilet. I was never like this before I slept with the girl and obtained the redness