mastrubation

hi i am a 21 year boy & i started mastrubating @ the age of 16 & since then i have been mastrubating frequently but know i have got 2 pimple like formations but it is a bit hard & granular (no puse) on the outer skin of bag containing testis & not on penis .is this due to mastrubation ?
if so is it something serious & what is its solution

Perhaps this is nothing serious and you can just relax as the two pimples that you noticed on the scrotum could just be the swollen hair follicles which can occur from time to time in your genital area, it happened to me a few times, I thought these were regular pimples and I tried to squeeze them but nothing could come out. I just let them be and they dried out and disappeared after a while.
On the other hand, these could also be the genital warts, a small cauliflower bumps that occur in your genital area, they are a kind of a sexually transmitted disease and if you had the unprotected sex you might have got them. These are usually dry and firm without pus that could be popped out.
Whatever these pimples you have are, you should go check them out with your doctor, and you will then be clear with what they actually are.