Mass behind beak
Welcome to BYC. It could possibly be canker or trichmoniasis, a protozoan infection which causes yellow to gray patches inside the beak and throat. Fish Zole (metronidazole, Flagyl) 250 mg given orally every day for 5 days is the usual treatment. Some prefer to cut the tablet in half, giving half in the morning and half in the evening. Acidified copper sulfate is used 1/4 tsp per gallon of water for 3 days each month to act as a preventative, since this is a contagious disease to other poultry and chickens.
Edited by Eggcessive - 6/27/16 at 8:04pm