I agree with Falsified on this one. These threads are a little scary for me, because I know this is a common feature of stimulant usage, but I would hate to send someone away with a dangerous condition like gangrene. All I can say is that you should monitor the situation closely and trust your gut. This is not a situation in which you need to tell the ED that the condition is a result of stimulant use. If you have any doubts I would go to the ED. I know it sucks, some people hate hospitals and it can be potentially embarrassing, but you get a clean bill of health and peace of mind.
I missed this on my first go-around. We also can't rule out the possibility that this is all unrelated or only partially related to the Cocaine usage. As a complete theoretical here, perhaps you have poor circulation/a heart condition of some kind and the Cocaine has only exacerbated it or caused it to become apparent. It sounds like this is what you would call Raynaud's Phenomenon. That doesn't really help, but it will help you articulate to others what you believe to be happening. I know 100% that Raynaud's Phenomenon is a well-known side-effect of stimulant usage. I am just unsure if the presence of these symptoms implies something above and beyond "normal".
Definitely let us know if you have any questions at all, but if you suspect the condition is worsening or just not improving, you know what I'm going to say. (Medical Attention)