Dermatillomania/Skin picking disorder??

[flamingamahinga]

(I'm a 17-year-old man) So for the majority of my life, I've scratched my skin due to psoriasis (which I think makes it even harder to stop/control myself).   But in the last year or so I have been compulsively ripping open scabs and making wounds larger with little regard for where I am or how much blood there is. It's gotten to the point where I ripped open a scar, (a newer scar, but a healed scar nonetheless) I have re-opened the scar 3 times, and now it's the size of a nickel. I have scars from scratching at scabs all over my hands, arms, legs, and ankles. I don't know how to stop.  The thing that scares me the most is the urge, the need to rip open and bump or imperfections on my skin, and once I start to dig, I can't stop. I HAVE to clean out the wound of the scab tissue, or at least until the urge dies down. I have literally taken nail clippers and tweezers to pick at the scab, making it worse. I need help...