Is it normal that i squeeze my skin?

For the past few months I've noticed that I've gotten myself into a quite nasty and weird habit. I think it started when I first found a small pimple on my arm, I hate pimples so I popped it. After that I've kinda been addicted to "popping arm pimples" EXCEPT there are no pimples on my arm. So I'm basically just squeezing the skin on my arm. Sometimes I'll be sitting there for a good 10-15 minutes and not realize that I'm doing it. As a result of it I now have many small black scars all along my arms, which used to be smooth and clear. Another weird thing about it is that I quite enjoy it, even the pain I get from it is some what enjoyable to me... So is this normal? But most importantly is it healthy?