Hello I Injected Crystal Meth Into My Left Upper Forearm,

Hello I injected crystal meth into my left upper forearm, and I drew back blood no problem.. so, I pushed the substance in. When it was all in I was going to proceed to pull the needle out. When I did I felt and very shortly after (approx. 1-2mins) I realized that my forearm had begun to go numb. About, 10mins. later, the area that was numb had gotten even greater. It almost resembles the numb feeling of anaesthetic. Is this something that could be in the substance? Or is their a possibility I hit a nerve? .... Do I absolutely NEED to go to the ER? (would prefer not to, only if I NEED to)