Dirty hands

I've been biting lately. Not other people but myself. Although, there was a short period of time in college in which I was biting other people but that's another story. I bite the back of my hand, right where the middle finger meets the rest of my hand on the top knuckle. I don't bite till it hurts. I just need to feel the skin in my mouth. Some times the urge is so intense it drives me mad.
It does so because due to my occupation, my hands get dirty at work all the time. So, I need to constantly clean them or I will be sticking my filthy hands in my mouth. So, now I have two urges fighting each other. There is the need to feel my rough skin in my mouth and the need to wash any bacteria off my hands. I want to put my hand in mouth very badly but due to the nature of my job I won't be able to get to a sink for a few minutes.
Sometimes I lose the battle. I cave. I shove my knuckle into my mouth before I get to clean it. I also stick my index finger's knuckle in my mouth. I bend it and shove the callused middle knuckle up against my gums. I push until it starts to hurt. Many times, also dirty.
Now, I have canker sores in my mouth. Oh well.