I am 18 and up until now had no real concerns with my genetalia.
Last night I was masturbating, and when i beat it, I do a proper job on it.
It started getting a little tender to rub on the part of the surface you can easily see, top-down, on the shaft.
It did not hurt when it was flaccid, and but i "tested it" later on it was still sore. Afterwards, a small vein to the side was tender, and some small bumps developed a bit to the right(not right beside it.)
The following day, the bumps have disappeared really, still tell where they were, but not easily. No problems with erection and ejaculation, but it is quite tender. What did I do to it, and will it be OK now?

Basically you hurt it,so don't "beat it". Joking aside, you over-did it. You were a bit too rough. The vein that popped out, was hurt (thrombosis) causing it to swell. You need to back off a while and let things heal. Next time be a bit more gentle with your unit. It's the only one you've got.

Also you might try expermenting with some lubrication. Saliva works pretty good and it's always there! Also some hand lotions, baby oil, K-Y jelly and even olive oil! Be careful with the equipment but not to worry. I've had the same sorta experiences after being to agressive! You'll be fine but give it a rest and take good care of it for a while!

Oh thank God. That is exactly what I needed to read. Thanks guys.