I Have An Old Self-inflicted Scar From A Finger Nail

I have an old self-inflicted scar from a finger nail scratch that is about 2-3 months old. It has some really really itchy bumps on the scar, and this is not the first time this has happened to one of my finger nail scratches. It itches so badly I feel like I might pop the bumps I scratch. So hard! I'm at a loss, can't treat what I don't know.
Please please please help before I go crazy so to speak :)
Thank you for your time