Hi thanks for your question.
You’re having bumps on your chin with no relief with antibiotics. Upper part of chin that is lower lip and area below the lower lip is known for herpes Zoster
that is viral infection. Viral infections don’t respond to antibiotics. If your Doctor is sure this is not herpes, then chances are that the bacteria’s are resistant to antibiotics you’re taking. I would suggest you to either change the antibiotic or send the materiel coming out of bumps or inside the bumps for culture sensitivity. So that appropriate antibiotic can be prescribed to you.
Hope this answers your question.