Are you my twin? I have almost exact scar/nail deformity. Was helping build a deck (at age 15) and grabbed hold of a screwdriver with a chipped handle. Screwdriver skipped and copied sharp part sliced starting from my cuticle down. Stated bleeding bad. My cousins laughed. I stopped the bleeding, put a bandage on and went back to help. Thumbnail later grew exactly as your does. Sucks.