Hi, not sure this will help, but my husband gets canker sores and he takes L-lysing (an amino acid i think) for 2 or three days and they always clear up. Good Luck
Anna

Cankor sores can have a lot of causes. The major cause is too much fruit acid, such as lemon, lime, grapefruit, orange juice, tropical fruit. Some body types just can't handle a lot of citrus. Other acids like meat and refined sugars, processed foods, coffee, also contribute.

Toothpastes with a lot of sudsing agents can upset the delicate balance of the mucus membranes and so it's best to switch to just a baking soda toothpaste for awhile. Gels are particularly bad.

There's usually a lack of good microbes (acidophilus) so drinking is highly recommended.

Garlic and onions (ever make French onion soup?) are very helpful.

Avoid hard candy, lozenges, as constantly having sugars in the mouth changes the pH balance. Some people just have a more acidic pH balance in the mouth. Sometimes this is due to a deficiency in base/alkaline minerals and digestive enzymes.

Most common deficiencies linked to cankor sores are: Iron, folic acid, Vitamin B12, Zinc, A/Beta Carotene. So cod liver oil, calves liver, nuts, and hot whole grain cereals are highly recommended.

and the doctor said it was a very common virus that each and every one of us get..only most get it within the first 6 months of life...anyway, the l-lysene is very good...for the pain, tho..
get some liquid benadryl(sp)..the allergy medicene...swish it around and spit out..use as needed as long as she spits it out...and yougurt...yougurt is very soothing and nutritious to boot...she can even mix the benadryl with the yougurt for a rinse...

I get canker sores a lot too. Lately what seems to bring the quickest pain relief and improvement is mixing acidophilus powder in a little water and using an eye-dropper, putting a few drops right on them -- I try to dry them off first. (I use the eye dropper because I don't care for the taste.) When I have more than a couple or they're unreachable, I add a little more water and swish it around and swallow.

I hope this helps you and your little one!
Michelle