I know how frustrating it is to face the issue of persistent acne.
There is no real evidence that skin gets resistant to topical products but obviously anecdotal accounts would suggest otherwise.
To cut it short, it sounds like you might need some oral medications like doxycycline or isotretinoin to improve the acute flares first, while using a appropriate skin regimen. From personal experience myself, when facing a flare we tend to overdo things, be it using OXY 10 five times a day and having chemical burns, or washing our face 10 times a day.
Medicines I feel can be a great bridge to stabilising your skin, whilst starting a suitable skin care series.
Don’t lose heart as many have walked this path before. Consult your doctor and treat early to avoid further scarring as well as treat the existing scarring. Best of luck!