self harm scars and pain

I have old self harm scars on my thighs which were deep. They went down to a white layer of skin when I continued to cut until there was no longer blood coming out of the wound. A year later still extremely big scars, but they hurt? Shooting pain like when I first cut my thighs open. When will this end and why's it happening? Some times the pain is so incredible that I feel like I can't move.