what do you think?

ive only just found this site do bear with me... for the past couple of years ive suffered with acne and like any teenager i couldnt resist picking at my spots. im now 17 and cant help picking at my skin, regardless if theres anything there or not; half of the time i dont know im doing this and only realise what im doing when someone (usually my mum) tells me to stop it. over the past few months this is getting worse and worse as i cant stop picking at myself, especially at my upper arms, back and sholders to the point where im creating scabs from nothing. this has resulted in scars accross the lenght on my upper back and all over the tops of my arms. if i find an odd spot i'll immedialy pick at it despite what im doing and will attack the surrounding area, even if theres nothing there. if i cut myself i'll then pick at it and eat the scab (disgusting, but i can help myself) to the point where a small cut takes 3 or 4 weeks to heal. also, i bite and gnaw at my nails and cutilces, making them bleed - even though it hurts i cant stop. when im not picking im constantly itching myself and its driving my mum crazy! also oim constanly figiting and connot sit still, even when im watchin t.v. i'll subconciously play with my hair or shake my feet or something. i dont know why i do this because ive had a good childhood; i think the problem is that im pretty hard on myself ive never had a good body image and i feel that my brain cant switch itself off, so i dont sleep properly either and can have sudden mood swings. last week i was crying uncontrollably, causing my parents to think i was using drugs or prengnant - neither of these are true - and couldnt beleive me when i told them i didnt know why i was upset, causing me to pick at myself more visciously. does anyone think im over reacting or have an opinion? i'd be glad to hear anything you have to say, no matter what it is.