My 10-day-old baby has a blister under his tongue. I wonder what it could be. Should I consult a doctor?

If your 10-day-old baby has a bubble under their tongue and it doesn't seem to be causing any issues with feeding or discomfort, it may be best to wait a few days to see if it goes away on its own. If it is still present after a month, it would be a good idea to consult a doctor for further evaluation.