R.S.
My daughter had this and the maalox mixture helped. I could tell it helped because she wouldn't eat or drink anything and then after sipping on that mixture she would eat a bit more. It is really just to numb the mouth so she could eat a bit. It took 3-5 days before she felt better. She got it a second time 6months later, once her baby sister was born and that time I discovered benyadryl has the opposite affect on her. She woke up halfway through the night and was wired, so I didn't use it that much that time around. To my knowledge it hasn't happened again.
I sure pray your little one recovers quickly.