I can relate so well to your urge right now. I think it is pretty common to have these urges even when there is no event that precedes it.

I often find myself sitting around the house, either at the computer or watching tv or doing my college course, and all of a sudden feel the urge to just start cutting. I can almost feel the blade against my skin.

I wish I knew what causes it or what could prevent these urges from surfacing so I could help you out more.

Try to hang in there and distract yourself right now.