This sounds to me like a salivary gland blockage,sometimes known as a
ranula. Depending on the symptoms the infant is having, there are 2 courses
of treatment. The first, if there are no difficulties feeding, is benign
neglect. In other words, these things usually self-resolve. In a case
where the infant is having trouble feeding, I would refer to a pediatric
otolaryngologist for an -otomy procedure.
Terry Lynn Dise, MD