If you are otherwise healthy, Angular Cheilitis is tyically caused by drooling while asleep or at least accumulating saliva at the corners of the mouth while sleeping. There it can collect bacteria or yeast, causing redness and splitting at the corners of the mouth. Bet you sleep on your side..... Your doctor or dentist can prescibe NYSTATIN ointment (costs $4 at Walmart and Sam's Club). Apply it to the mouth corners several times a day and at bedtime. Learn to sleep on your back (can't drool or collect saliva while on your back). I suffered for about 6 months until I took this approach. I hate sleeping on my back but have learned to do so. So far - no recurrence. God Luck.