“Bump and redness after IV meth injection?”

I'll bet your friendly neighborhood drug dealer reassured you that the meth he sold you is sterile, FDA-approved, and pure as the driven snow. Very few addicts would believe him, and nobody should. You have no idea what he cut the meth with. He may have swept up his kitchen floor that morning, picked out the dead flies, and cut your meth with the remainder. The good news is he probably didn't use soiled toilet paper.

You'd know it if you had hit an artery, as blood would have come gushing out. Instead, you injected some sort of gunk that caused an infection. Because you injected into a vein (that's the whole point), it's entirely possible the infection is spreading throughout your vascular system, causing total-body sepsis. You most certainly have a localized infection. Get your butt to your primary care physician.