I Missed A Small Shot Of Meth In My Left

I missed a small shot of meth in my left arm and it started to swell and went numb so I started to run my arm under warm water and next thing I kno the swelling goes up my arm, then it spread to my chest and now next thing I know my whole body from my neck down is swollen. I do tkno what's going on. Can you tell me what i should do?