Hi there ~ I understand your concerns. Use of injected heroin comes with risks. The foremost among the risks include the risk of sexually transmitted infections by using bad infected needles. I also believe that misuse of these injections may lead to complications like phlebitis which is inflammation of the veins and also connective tissue and muscle if not injected in the correct position. You need to consult a local doctor to see if you have infection of the fascia (fasciitis) or another condition that needs to be treated with antibiotics. I wish you the very best in recovery. I hope this helps. Take care and have a lovely day!