My teenage son has a real problem..i dont know what to do.?

Ever since Armando hit puberty, Ive noticed that he spends a lot of time alone in his room. I've accidentally walked in on him numerous times, nude on his bed, pleasuring himself. I know this sounds like a joke, but I am 100% serious. I think he might have a problem. I am very worried that his behavior will make him anti-social. Has anyone had this problem with their kids, and how have you dealt with it? Any answer is appreciated. Thank you very much.