Sorry, I misunderstood the original post. If you have an infection from an IM injection go straight to a doctor, don’t fuck with it. to much to type on the phone but the jist of it is most infections come from bacteria on the skin getting into the injection, not from bad gear.
This means that it’s most likely staph, MRSA (methicillin resistant staph) or even worse cellulitis (not the nasty leg fat). These things are not commonly treated with oral antibiotics, they need IV administered antibiotics like vancomycin, zyvox, cubicin, etc.
especially if the infection moves from the muscle tissue to the blood stream you can go from perfectly fine to with a red spot and fever to dead in 24-48 hours. If you’re lucky it’ll stay in the muscle and in 24-36hours your entire limb you injected will be red and swollen and you’ll just have to get part of that appendage and surrounding muscle cut out to stop the infection, spend a few days in the hospital hooked up to IVs then start months long rehab from whatever area they had to cut out.
Point is don’t listen to anyone about IM infections, those infections have plenty of blood flow and nutrients going to them and can literally spread fast enough to fuck you up in a matter of hours. If you really want to be a dumb fuck, take 1g of penicillin and 1g of Zpack and if it doesn’t stop spreading and/or get better then go to the doctor. If it does get better take 1g every 12 hours for the first two days then 500mg twice daily for 14 days.