Its normal for your testicles to move around in the scrotum. They just kind of float around, and they can move up and down a lot depending on temperature, sexual excitement, nervousness, and a bunch of other things. They're not anchored down in the scrotum so they can move quite a bit. They are attached to the body with the spermatic cord at the top, but they have a big range of movement.
As for the bumps on your foreskin, I'm not sure what those are. It could be irritation, so you may want to try masturbating less or with lubrication, and see if it gets better. It could also be a fungal infection - hard to say.
|