The wound

I have this wound. It has been there for years, never properly healed, scanning over but never given enough chance to form enough new tissue to recover completely. Sometimes the scab gets knocked off, unexpectedly, unavoidably. Sometes I deliberately pick it, to see if it still hurts. It does. It hurts as much now as it did when it was fresh and new and I was unscarred, untainted. Sometimes it just opens for no particular reason. Blood everywhere when I'm least prepared for it. Occasionally it gets infected and I worry I'll have to cut my arm off. How will I manage? What will it feel like? Once open and sore it takes a long time to reform the scab, the throbbing pain a constant reminder, the affect on my functioning a sign. What caused this injury? Why will I never heal properly? What can possibly hurt this much? Surely there's something that can be done? Is there something wrong with me that makes this so painful? Why? Autism.