My 2 month old son has a white bump on the center of his tongue, what could this bump be? he sleeps with mouth open and has a stuffy nose.

Needs to be seen: More important that what it could be, is what it is. Unfortunately, this would have to be seen by a dentist, preferably a pedodontist, or pediatrician in person in order to give you an accurate answer. Call for an appointment.

Nasal saline: For colds, gently removing the nasal mucus with saline and a bulb will help your son to breathe through his nose. The white bump on the tongue should be checked by your pediatrician.