Dark Colored Urine

Need a bit of advise, if anybody can help then great.

A couple of months back I noticed my urine was rather dark, and I would feel like I wanted to go to the toilet but then there would be very little urine. I went to a doc and he gave me some antibiotics for a UTI. The antibiotics seemed to clear the UTI, however since then my urine is still not clear. The very off thing is, if I drink a few pints of cider it is very clear. I drink a lot of water each day and that improves things. 

When my bladder is full, I can feel something very faint inside it, like a small button. I am wondering if anybody has experienced anything like this? I am 37 years old, and male. I am in decent enough shape, maybe 1 or 2 pounds over weight but I walk a lot and eat proper fresh food.

I returned to my doc last week and he gave me some more antibiotics to treat chlamydia even though I was telling him there is no way I have that. He said if these do not work, he wants to do a full STD check which is quite expensive. He seemed to be dismissing me as imagining what I feel.

When he checked my urine, he dipped a bit of paper into it and waited about a minute and said everything appeared fine. Does anybody know what he was checking?

Any advice/insight would be very much appreciated.

Btw : I am the polar opposite of a hypochondriac, so its very very unusual for me to be anywhere near a doctors room so I aint making this up.

Thanks