I have had angular cheilitis at various times in my life, as a young adult and into middle age. It seemed to occur when I had a virus. I was told by a pharmacist to use Vicks Vapor Rub on the corners of my mouth and it does the trick (at least for my situation). I always keep a small container of VVR even when I travel in case I feel it starting up. The earlier you catch it, the quicker it goes away. If you use a different brand, make certain it has the same active ingredients. Once I bought a generic brand and it didn’t do anything. Once I compared the ingredients, I saw they weren’t the same.
I have also suffered from horrible mouth ulcers (not at the same time as angular cheilitis) and taking acidophilus and eating a lot of yogurt helps keep them at bay. I also avoid taking Augmentin as this will cause me to have multiple large, painful mouth ulcers.