Why is my Australian Rainbow Lorikeet getting a small bald spot on the back of his neck?

I have a beautiful 6 year old Australian Lorikeet, and recently i noticed an odd bald spot forming on the back of his neck. It looks really out of place and is can basically see to the skin. I have had him since he was only a few months old, and I have never come across something like this for him. He still seems pretty chipper and happy but im still worried. Im planning on a making a vet appointment for later in the week but still thought I would ask for some advice here.