Unfortunately hematomas frequently occur bilaterally. They are caused by broken blood vessels that lead to blood/hematoma between the skin and the cartilage. Ear scratching, head shaking, or rubbing causes the damage to the vessels. This is often triggered by allergies or an ear infection. Have your dog examined by your veterinarian to see how far the second ear has progressed. It may be possible to pressure wrap the ear to prevent further damage. It is likely that he will need a second aural hematoma surgery.
My Dog's Ear Flap Is Swollen, He Had Surgery For An Ear Hematoma Now The Other Ear Is Swelling, What Should I Do?
Ice packs are good for swelling but it being for a dog, I doubt your dog will like this and let you do it. I would call your vet in the morning and see what they suggest and see if their is anything else you can try.