Apologies for the NSFW post. I'm trying to gauge how concerned I should be and whether I need to make a GP appointment. I am male, 35 years old, white, average height and build, no significant past medical history.

Yesterday I engaged in consensual BDSM sex for the first time. Something unexpected happened, in that my partner bit down on my penis mid-shaft and roughly squeezed my left testicle. This was startling and painful, but we were both more shocked by the small drop of blood that immediately appeared from my urethral meatus. We stopped, and I took the opportunity to go and empty my bladder. I kept my pants on the rest of the night, we made no further attempts to engage in oral sex nor any penetrative sex.

I've seen no more blood since that initial single drop, not last night nor at all today, and it has not been painful to urinate today (last night it was just a bit sensitive the first time). On my penis, there's no swelling, redness, bruising or any other visible mark, no pain on urination, maybe the faintest general discomfort sort of localised towards the tip. My left testicle feels a bit tender and could be a little larger, or it might just be in my head, if it is swollen it is certainly subtle (my partner didn't know this but my left testicle has been aching on and off for over a year, for which my GP prescribed "watch and wait"). I haven't tried to get erect since last night so I don't know if that would cause any pain.

This has all been somewhat mortifying. Obviously the safe answer is "go see a doctor". I'd rather not, especially not if it will just be a wasted trip where they say "you look fine, no obvious signs/symptoms, come back if it gets worse". Not that it should matter, but I know it does - I'm in the UK, on the NHS. Is it fine to just skip the humiliation of a first trip and only go if anything changes? Or is there something I don't know about this kind of small injury that could come back to "bite" me later?