The best way to heal the wounds is to keep them clean and try to avoid reopening them. You could try covering the wounds with plasters to help prevent you interfering with the wounds without realising.
Have you ever had a fidget or similar? Maybe having something to fiddle with might help to reduce this if it's something of an anxious fidgety habit.
In terms of dissociation, are you receiving any professional support for managing this and have you tried any grounding techniques?