Hey buddy. You have the right idea with the compresses and topical treatments. There is not much you can do at this point other thane manage pain, if that is a problem and wait and watch. If the missed shot dissipates without consequence, then you're fine obviously, but if you develop and infection, you may need to seek medical attention. Methamphetamine is among the drugs that I would consider more "corrosive" than others. It seems to have a tendency to cause problems.
I would keep applying the compresses as needed, pop some Acetaminophen (Tylenol) or what have you for the pain and make sure to get it excised if it develops into something more serious, You will know if something is not right. If it doesn't start getting better within a matter of days, it might be a problem.
Keep us posted man. I don't want you to get hurt.
