Painful masturbation only when laying down?

So I've looked everywhere for some kind of answer to this but I haven't found anything similar to my experience.

This started earlier this year, I was masturbating in bed and it was hurting like hell, specifically a stinging pain along kind of the left side underneath the head of my penis so I stopped. Later in the day I noticed blood in my underwear, and even more later, it also kind of stung when I peed too hard, I had to kind of "clench" or like, hold back the stream if that makes sense.

I went to a doctor, got a urinalysis, got std tests, had the doctor physically examine my penis, and was told that I probably just passed a kidney stone or had some microtears inside my urethra so I left it alone for a while. The blood stopped appearing pretty quickly, like 2 days later, and the painful urination got a lot less intense though it is still present, barely noticeable though. That stinging when I masturbate is still just as bad, but it's only when I'm lying down or going too fast/intensely, and there are no other symptoms, no blood in semen, no visible irritation, no trouble getting erections. Is this something anybody else has experienced? I'm mtf and have been on hormones for close to 4 years now, could that be causing it?