Possible neurological problem with horse?

Just recently, my breeding stock paint mare, pebbles, age 18, began displaying odd symptoms. Actually, it was this morning that they really showed up. We called the vet out because she was colic-y, so he did the whole treat for colic thing. However, she also had non-colic symptoms, such as poor balance, odd ear placement ( like this: \_-- <- those would be her ears.), a lot of head shaking and eye nystagmus. The vet believes it could possibly be EPM, so he's gonna have her tested for that. I noticed last night, and again this morning, that the hair on the inside of left her ear is wet, as if it were coming from the inside of her actual ear. Then i noticed that her eyes were moving involuntarily to the left. I'm thinking, maybe it's the liquid in the inner ear, like we humans have that keep us balanced. If that was leaking, could that explain her balance? Can it even leak? What is your take on this?