Need to urinate/feeling in penis
I am wondering if anybody can help me. About 2 weeks ago I noticed that I constantly needed to urinate, at first I thought it was a urine infection so I went to the doctors, did a urine test and was just told to try to train my bladder (thought I had overactive bladder syndrome) and drink cranberry juice. That didn't really work so I went to the hospital and did a urine test there as well (both came back negative). I went back to the doctors a few days ago, had a prostate check (that too was fine) and was given a months supply of Tolterodine tartrate.
The problem still persists though, the sensation is almost like there is a blockage in my urethra/the urine is building up in my penis. The main things that seem to help are paracetamol, getting an erection and kegel exercises (which I am not even sure I am doing correct). 2 months ago me and my g/f both had STI checks which were all clear. For the last week or so all I have drank is water and cranberry juice, a normal amount (not drinking less or more than usual). Any ideas as to what may be up and what I should do? I have noticed for a while I have a dull ache in my lower back (I play lots of tennis and badminton) and I am actually having physio in about a week, should I mention something then? Also, as of writing, the last time I ejaculated was 2 days ago and it was very watery, I sort of wondered if the water had been blocking something and it was expelled when I ejaculated (graphic I know).
Any help would be much appreciated.