The ear flap or pinna is made up of a piece of cartilage covered by skin. Sometimes you will get bleeding between the layers that pushes the skin off the cartilage, and causes a lump. We call this pocket of blood a hematoma, and because it is on the ear, it is classified as an aural hematoma.
Ear infections (otitis externa) are a common occurrence in our pets and can cause scratching, rubbing, and head shaking. Some pet owners will notice a dirty ear that needs to be cleaned all the time. A normal, healthy ear needs no intervention, so a build up of wax means something is wrong.