Can't Animate Half of my Sprite

So I'm just making a simple idle animation but whenever I try and animate the head of my sprite in the animation window, it kicks me out of the animation I'm working on and says "To begin animating Head, create an Animation Clip", but I want to animate the head of the character with the rest of the body. I can click on the tail and it will create new keyframes in the animation window, same for the legs, but when I click the head I can't do anything. It seems to act like the head is its own character.