Welcome! My name isXXXXX am a 2003 graduate, and currently a Medical Director of a veterinary hospital.
I am sorry to hear about this concern for Ernie.
What you are describing is likely consistent with a aural hematoma. This is when the ear flap ruptures a blood vessel, and the ear fills with fluid. Unfortunately, simply draining it often does not solve the problem, and it will continue to accumulate fluid. The links below will help you to understand the condition better, as well as, treatment options. I am including information about ear infections inside the ear canal, since that is the most common explanation of what causes a hematoma to form. Aural HematomaAural Hematoma (excellent link)
Also, Hematoma are also caused by or accompanied by ear infections (otitis externa):Otitis Externa (Ear infection)
Unfortunately, if the ear feels like a balloon that fluid cannot simply be drained out. Often a ear surgery is needed to help resolve the problem.
it is not necessarily an emergency, but the ear needs to be evaluaed as soon as possible, and the ear canal evaluated for any primary infection that caused it in the first place.
I hope that information has been helpful.
Please remember to select Reply to Expert, if for any reason you need further clarification, have more questions, or were expecting a different type of answer. Prior to leaving a feedback rating, which I greatly appreciate, my goal is to provide you the best answer possible.