Could I have an STD?

[Paraglas]

I'm going off my head with worry.
I have had a number of incidences with other males in toilets. Sorry generally mutual masturbation but have had a few incidences a few years ago where they have performed oral on me.
I've been tested after the last time I had oral performed on me and all clear. Never had an oral test done,but we are talking a couple of years ago.
My throat has been sore since last Nov. I have got GERD, but medication isn't stopping it and worry that I have somehow passed myself an STD by eating my own semen. Done this only once.
Also my mouth, esp my tongue is sore and have frequent red patches and an occasional small white dot on the inside of my cheeks.
I realise this could all be GERD,but my mind is working overtime.
I also have a small black but on my tongue this morning and brushing is not removing it. Im worried sick it's going to be a wart or some std. I also masturbated someone for a few seconds (nothing happened) on Fri and when I got home half an hour later I forgot and touched my tongue and worry I could have passed something here as I hadn't washed my hands.
I know I'm probably being stupid but I'm so worried about it and don't know where to turn.