Has my toddler got cold sores or foot and mouth disease?

my 17mth daughter has had a severe outbreak of mouth ulcers in her mouth, on her tongue, inside her gums, on her lips and on her face. they are now appearing on her fingers presumably from touching her face. she doesnt swallow, so is dribbling badly, hasnt been eating or drinking. the doctor said its cold sores but the medication hasnt been giving her any relief. the pictures of them both from internet searches are so similar i cant work out what it is. any suggestions? has anyone had the same issue with their children? it is heartbreaking to see her in so much distress. thanks in advance. x