Scout's eye seems to do that every few months. I asked the vet because I kept thinking she was getting scratched by Jazz when the wrestle but he said it was due to a clog tear duct. That doesn't make much sense to me because her will tear, especially when she eats but he insist that is common. It usually last a few days, her eye will look a little red, watery and sometimes even some whitish or yellowish discharge. It clears up in a few days and she is fine. She never acts like it hurts either.