Hi, I had a German Shepherd with a similar problem. I tends to happen to floppy eared dogs as they shake their heads and flop their ears around. It's been years since my dog (long gone now) had it but I believe it has something to do with the cartilage in the ear. If I remember correctly there is a surgery they do to correct this problem. Best take him/her to the vet and get it fixed up.

It's called a hematoma and is caused by trauma to the ear (by banging it agaist something or by shaking the head and causing the ear to hit against the head). The ear forms a fluid filled pocket that feels like a squishy pillow. There is a surgery that can be done to help build scar tissue in the ear and keep it from refilling. Here's a link that explains the surgery pretty well.http://www.thepetcenter.com/sur/hema.html

Hey you guys are pretty good. I have had collies all of my life and now a golden, this is extremly usufull to know. Thanks