Hey sorry for the delay in response. I cut down meat to one meal a day (if any) and do not eat red meats. They do not digest well for me.
Cheese and dairy were the worst. I follow a FODMAPs diet now which helps.

The peroxide I use is the kind in brown bottle from pharmacies. I soak a qtip with it and clean out ear with it. I let it dry. I do not flush it out with water. Occasionally I will pour a few drops into ear and clean that way. Wipe twice with q tip and let dry. When the smell was still behind my ears I used Acne cream (benzoyl peroxide) back there and left it on all day. It dries out the skin and kills bacteria on the skin. Good luck and I hope it works for you. I had that same nasty dog ear infection smell you talk of.