The Apple Cider Vinegar doesn't do anything for Respiratory illness. It does help support gut health, & digestion. Probiotics is good for gut health, & immune support, but it doesn't do much for respiratory illness.
This is entirely off topic. We're on the subject of combs.
That's not that bad really. It's only at the tips.
Best thing to do is not to mess with it, cuz that'll make it worse.
For large single combs, & wattles on my boys I do dub them for frostbite prevention, so I can avoid possible infection. Also it prevents hen picking.