He first had a blue cere but it changed into brown. I dont know exactly how long its has been changing I think its has been a year with his changing cere. I dont think is testicular cancer because he doesn't have any bumps any where. Also I was reading that is maybe male dominance issues, he does live with another male budgie and he is more dominant so maybe it's that but I am not sure. I need help and i don't know what it is. He also looks healthy he talks and eats and do all the normal stuff. I also have him for almost three years and I dont know how old he is cause my aunt found him in the streets tired and she brought him here and I am the one taking care of him since then. Anyways I am very confused on why his cere changed can you guys give me some opinions.