There is NO medicine we can tell you about. The bird has to be seen in person by an Avian Vet only in order to diagnose and treat a problem. Without a diagnosis, there can be no treatment. Do not give any home remedies and no over the counter meds because until you know for sure what kind of problem this is, you cannot treat it. Also, take bird to only an Avian Vet because dog and cat vets do not know what they're doing with birds and can make problems worse and still charge you a lot of money.
There is something very wrong here, and it needs to be diagnosed and treated by an Avian Vet.