I am not sure that what you have is not perioral dermatitis but rather plain old acne. I don't recall seeing perioral dermatitis on the lower forehead.
Either way, treatment takes 4-8 weeks to see results, sometimes more. You can't tell at this point what will happen unless you stay on the medication. I am a little perplexed by your repeated "hives"--I haven't seen hives come from either minocycline or eryhtromycin, and while anything is possible, these medications are unrelated to each other. Perhaps these are just regular hives that people get who aren't on anything, or else maybe they aren't even hives.
My advice is to stay the course and stay in touch with your doctor about hives and other symptoms. Clearing this up may take several months, but please rest assured that there are plenty of other options for you to access if needed.
Take care.
Dr. Rockoff