From the kind of lesions you have described it seems that it is fever blister also known as cold blister or herpes labialis.
In most of the cases it subsides on its own and only conservative treatment is needed. Maalox is an antacid and usually used to treat gastric ulcer.
You can use ultracare or other oral anesthetic
gel over the lesion. Also use antiviral
ointment thrice a day as this prevents the spread of virus. Give multivitamin
supplement as it helps in early healing of the lesions. If pain is severe you can give her acetaminophen