What Causes Itchy Pimples On Thighs And Arms?

Hello, im having problems with my skin. Like 3-4 months ago i started to get itchy on my thighs and arms and now i have pimples/i also have been addicted to scratching them and till this day i still scratch. It itches so much. And i dont have bedbugs,nor bugs in my apartment. Do i have a disease