Skin infection

This is where I am now—after posting on numerous vets’ and animal welfare subreddits multiple times and visiting countless vets across South Delhi, I’m at my wit’s end. I even bought my cat an anti-flea and tick collar from Hartz, but there’s still no resolution. I’m turning to this community in the hope that someone here has successfully helped their beloved kitty. My cat has been suffering from this awful skin disease for the past four years.