Thanks for writing to us.
Black tongue in a two months old baby is only due to the pigmentation of the tongue. If the pigmented area is not increasing in size, there is no irregularity of margins or redness
or ulcerations then most likely it is a benign lesion and does not need any treatment. If the re is any change in the pigmented area then consult your dermatologist
for further investigations.
I hope this information has been both informative and helpful for you.
Dr. Praveen Tayal