I Use Cocaine Intravenously. The Spot On My Arm That

I use cocaine intravenously. The spot on my arm that I usually use has a scab, and when I try to inject anywhere near it, sum yellow puss comes out and it smells like fish. I tried to move the scab bc I felt that wasn't helping, and when I lifted it, it smelled even worse! What is going on?? Is there any way to get rid of it??