Bump under tongue, what could this be?

Many possibilities: Rather than recite an incomplete list of the possibilities, i'd suggest you get to a dentist for an exam to find out exactly what the bump under your tongue is. The underlying issues range from minor to serious so please get it checked out.

See dentist: There are a number of things that can cause a bump under the tongue. One of the most common cause is a blocked salivary gland and this will frequently resolve by itself. If this bump is increasing in size, lasts more than a few days, is painful, causes difficulty swallowing then you need to see a dentist or oral surgeon.