I overmasturbated a lot, but now i stopped it. and now my penis when no errection feels sometimes hard and shvireled up, but when i touch it it gets soft again. and also my prostate twiches sometimes. will i heal? is it bad?

One can try less...: Less friction, less force (fewer pounds per square inch, of hand force), and perhaps longer intervals between masturbation events. If symptoms continue despite thoughtful improvements in technique and/or frequency, then it will be time to get evaluated by one's primary care doctor. Remember, half the people in the world get a penis (just one per person) and have to make it last a lifetime.