Minocycline stopped working for acne (bacteria resistance) derm switched to ampicillin. how's this compare to tetracyclines? when will it start workin

Ampicillen: It may take 7-10 days before it starts to work. Tetracyclines appear to work better.

Heads up: I see that you are actually taking both isotretinoin and some nerve medicine. During your time on antibiotics, were you also using a topical agent such as the Retin A you also list? Antibiotics will fail otherwise. All acne is manageable nowadays if you have continuity of care. Best wishes.