I am 14 years old. And I have the same issue, my heart goes out to you. I have had this problem for about a few months and I have been looking everywhere for an answer. I was diagnosed with Dermatilliomania. Which is the compulsive disorder to pick the skin. I have been going to a psychologist for about a year for my OCD. It is very difficult to deal with and most of the times I just have to sit on my hands. A few tips of when you feel the urge to pick..
1. Sit on your hands.
2. Think of something else, haha like ponies.
3. Take a break from your work, I get stressed and I pick my scalp.
4. Find another hobby. Color, paint, jog, walk, write.
I am so sorry if this didn't help :(
Have you talked to your doctor who is prescribing the prozac about this compulsion? As with any compulsion, it becomes a habit and like any habit it can be broken. It is going to take work though. The picking may be helping you with your anxiety but it is creating a whole different problem.
My own suggestions would be first to talk to the doctor. You need to learn some behavior modification strategies in order to overcome this habit. Keep your nails short, as short as you can. I have even suggested that people wear socks on their hands or hats on their heads so that the picking cannot be done easily. If you do this, then you won't be able to pick "without realizing it." If you are doing it in your sleep, then try the socks on your hands and the hat on your head and see if this helps. You would have to take both off in order to do it.
There is a reason you are picking and it may be from when you had lice. This may be the trigger for the picking that has gone on since that time. A psychologist can tell you more about this. I think if you seek treatment specific to this problem, you will find that there are ways to overcome it. Best of luck.