That doesn't sound much like herpes, more like a bacterial infection (boil
); as you may know, such infections are more common in diabetics than people without diabetes.
None of the antiherpes drugs (acyclovir, valacyclovir, famciclovir) will interfere with your diabetes drugs. Presumably you are on acyclovir now? If not, get a prescription right away; it will help speed healing of your herpes.