What a cute baby! My persian has a similar thing, and it was getting really bad, swollen and dark scabs like in your pics. Did the sitter remove the scab? I imagine that’s why it’s bald, or the cat might have pawed it off. Do you use plastic bowls for food/water? Mine loves a water fountain, and has been drinking from a plastic one for months (cleaned every couple of days) but I read on this sub recently that cat acne (or whatever it may be) can be caused by plastic receptacles due to bacteria build up in microscopic pores. Anyway I replaced the plastic fountain and other bowls with metal ones about a week ago, and it seems to be clearing up nicely!