[Silvan]

Dear Ivan,
what you've described definitely is self-harm. Although we do not always think of self-harm when we hear the word 'addiction', it is an addiction. Why? Because the urge constantly becomes stronger and one harms themselves more each time as they get used to it.
Perhaps, except for the alternatives mentioned by Cassado, you could try setting yourself goals. It works quite well for me. What about telling yourself: 'I will not hit myself for the next 10 minutes' (and distracting your mind using the alternatives during the given time). Then you can set another 10 mins, 15 mins etc. until the urge passes.
Tell us whether these methods worked out.
Stay strong
Sue