Usually constipation, vitamin deficiency, indigestion, acidity, less intake of water, excessive intake of salty spicy food cause mouth blisters. Follow few tips 1.Include barli Pomegranate, Jeera, coriander, aloevera, amla, tendercoconut , honey, bootle guard in diet 2 chew mango or guava leaves 3. do regualr oil pulling 4.eat gulkand ayurveda medicines like Khadiradi vati, Tankan bhasma, triphal choorna also help

Hello there...I can understand your concern. There are a lot of causes for blisters around the mouth like herpes simplex infection, pemphigus, irritant contact dermatitis, leukoplakia, vitamin deficiency, behcets disease. She will need to be evaluated completely to find out the cause. Have some patience. Kindly consult a good dermatologist nearby for further evaluation.