Does anyone know of any reason why this may be happening? They are quite big and so painful for her, last month she had a bout of them that were so bad she could hardly eat for about 2 weeks, it was a viscious circle because it made her even more run down, she had them all up her tongue, in her cheeks, near her lips. She was given some treatment from the doctors and it did help but she keeps getting them still. She has good oral hygiene, brushes her teeth twice a day, rarely drinks fizzy drinks and only occasionally has sweets.