It is hard to picture what you are talking about, and there should be nothing under the beak, so I would say a trip to your Avian vet would be in order. If your little bird has not seen an Avian in a year or more, it's time to take bird in for an exam for infections, parasites and some blood work to make sure organs are functioning properly.
As I said, there should be no spots under their beak, and anytime you see or feel something that should not be there, an Avian vet will help in diagnosing and treating whatever it may be. Infections start out slow and work up into life threatening situations, so I'd take bird on to your Avian vet and have it checked out for your own peace of mind.
