Was Injecting Heroin In Hand Between Thumb And 1st Finger

Was injecting heroin in hand between thumb and 1st finger and missed some of the injection. Was sore for a couple days then a bump was noticeable. Then the next day my hand was swollen and I thought it was because I work with my hands. Well it's be like 3 days and swelling hasn't gone down and just recently a faint red line appeared from armpit to elbow in like a crescent moon shape. What can this be?