I don't really have any advice, but wanted to let you know my daughter does the same thing. She is 8 yrs old and does have both anxiety and OCD and this is just part of what she does. Like you said, she doesn't even realize she is doing it. She touches and picks at one side of her mouth, the skin around it, and gets red sores. Then she picks at the sores, making them worse. It is like a fidgety habit. We chose one word - cancel - to say when we see her do it. If anyone in the family sees her picking, we just say "cancel" and she puts her hand down. I have tried offering her different things to bring to school to fidget with, like a bracelet with smooth stones on it, a "worry" rock to rub, a stress ball, a koosh ball, etc, but she is too worried those items will get lost, so she won't bring them to school. But something like that may work for you, especially the bracelet idea. Find a bracelet that has smooth (or rough, whatever texture you like) stones on it and try rubbing or just touching them anytime you catch yourself picking. Hopefully you can transfer that need for touching onto something else. I think that is what it is, a need for touch. Do other things that you can to give yourself more sense of touch and pressure through out the day and you may not have that craving for picking at yourself. Good luck, I understand what it is like.
S.