Yeah, I dealt with this condition longer than most here.
Regular yogurt does not have enough probiotics in it. I needed a bottle of probiotics that came in liquid form. The milk in the product is drying, but I needed that to dry the moist part of upper lip so it could form a scab (or new layers of skin) to heal. I do not think I needed to apply it on my lower lip. I also swished it around in my mouth. It could be a bacteria problem, but I do not know if everyone would have the same strain of bad bacteria in their mouth.