i masturbate often almost everyday and sometimes its access . last night i masturbated and woke up to see a small bump on my penis. I'm had unprotected oral sex with a stranger 5 months ago and then i started dating a girl . ive had unprotected sex with my girlfriend for a while now and nothing's happened to the both of us ( note she was a virgin and had done nothing before in terms of sexual matters) . can somebody tell me what this is 
Leo, lumps and bumps like this are quite common - what you need to recognise that during masturbation the skin and ‘innards’ of the penis undergo quite a lot of friction. What you have is most unlikely to be linked to any of the sexual experiences you have had with other people.
Do you use any lube of any kind for masturbation? What would happen if you totally left your penis alone for 3 or 4 months is that all these kinds of marks would completely disappear and your skin would return to normal.
The best thing is just to get on with your sex life and self-pleasuring, and just enjoy! If you are not using a lube the ones to try are plant extract based ones such as Coconut Oil or Aloe Vera Gel, both are inexpensive and are good for your skin too - simply apply a very light film prior to masturbation and after you have taken a shower.
Don’t use the Coconut Oil for lube during sex if you ever use regular latex condoms however - you can get alternatives to latex ones such as polyurethane that are safe with Coconut Oil … !