I had a similar experience. I had sat on something which left several pieces of plastic imbedded in my thigh. I even went to A&E and told them there were pieces in there. They were adamant that there was nothing there. After pulling six pieces out by myself the wound finally healed almost overnight. What I am trying to say is, if you go to the doctor or a hospital make sure you present your case robustly if you want a good outcome.