I'd visit a dermatologist for a complete check up. The problem could be physical. I'm certainly no shrink, but I suspect some underlying emotional and mental issues. You may want to have a visit or two with a counsellor.
you need to get to the root of the problem. there is a deeper issue that you are not dealing with. You should seek some help from someone who can help you overcome past problems, but i hope you dont mind me saying that the only one who can truly set you free is jesus. ps...i have HAD the same problem.
I would usually say put a rubber band around your wrist and snap it when you feel like messing with your skin, but I don't think that would help in your case. You could write 'brake the habbit' on a piece of paper every time you feel like messing with your skin. Just keep writing it over, and over until the urge goes away. Keep the paper, and see how many times you had to write 'brake the habbit' before you got over picking at your skin. If you ever feel like going back to your bad habbit, look at the papers, it will stop you. :) good luck!
it might be an anxiety thing, i wouldn't suggest going to a counselor first thing, but do try to stop yourself, such as throw away all of the needles, and cut your nails if you scratch with them, and when you do it punish yourself by squeezing lemon juice in your mouth when you do it, if it keeps going on then do seek professional help. Keep in mind that you're not a freak, because I've done the same thing because of my anxiety, its normal, but at least try to stop before you start to lose blood, the longer you do it the deeper you'll get.
i have that same issue, i cant stop poking my skin or keep my hands off my skin. I know the triggers, but its not easy to stop. i just want to quit, i hate damaging my skin, try making a list of all the things that trigger it and then write another list of positive solutions