Hi and welcome to HCM.
Thanks for posting your query here.
In some children the tongue appears to be coated white what we call it as thrush
. But black or gray tongue seems to be any reaction to the medication which is given to the baby.
Please check the food baby is having without your knowledge. Sometimes it could be because of staining after having mulberries.
is not recommended for children below 12 years of age. If at all used it should be with the doctors supervision.
So please enquire about her food and get an appoinment with paed.
Hope this is helpful to you.