Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear about your fellow Cole's swollen, fluid filled ear with a sore towards the top of it.
Does this swelling feel like a water balloon?
Is it part of the ear flap?
Has he been shaking his head?
Does he now or has he ever had an ear infection, or does he just have the sore on the outside of his ear that he has been rubbing?
Does the swelling look like the dog in this link below? (can be smaller but this will give you a general idea) https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSP22YeYjTDsYPXpDMZCd5QG6g7BWmHlY59N2ZcNY7t_OfZh7qG
If so then this is likely an ear hematoma. This happens when a blood vessel in the ear breaks and the area inside the ear flap fills with blood.
It is usually from them shaking their head/ears repeatedly from an ear infection.
But sometimes they just shake their head a few times, hit the ear on something and a blood vessel breaks leading to bleeding.
In his case he may have been rubbing the sore or shaking his head because it is uncomfortable and that led to the hematoma forming.
If it is very small (nickel size) it may heal on its own just fine as the blood is reabsorbed.
You can apply a cool compress for 5 to 10 minutes at a time to the swollen area the first 24 to 48 hours, then pat dry and apply cortisone cream (like cortaid) twice daily to help reduce inflammation.
After 48 hours try a warm compress rather than cold to speed healing and improve circulation and then cortisone ointment.
But if it's larger then it may need to be drained and/or sutured so it doesn't refill.
If you notice any odor or increased waxy debris then he may have an early infection which started all this, and then he should definitely see his veterinarian for proper treatment no matter that size of the swelling is.
You can clean the swollen lump/sore area with a solution mix of Betadine solution and warm water. Mix the Betadine solutionwith warm water such that it is the color of weak tea, and clean the affected area twice daily. This is an antibacterial and will dry the lesion out to allow them to heal. It does stain horribly though so you probably want to do this outside. Betadine solution is available over the counter at the drug store, if in doubt ask the pharmacist for help.
If he is scratching at his ear quite a bit or seems bothered by the swelling you can give him Benadryl (diphenhydramine) at a dose of 1mg to 2mgs per pound of body weight orally every 8 hours (two 25mg tabs per 35-50 pound dog every 8 hours). This will reduce allergic itchiness and can make him sleepy which should help him leave the ear alone.
If he is rubbing the ear or scratching at it placing an elizabethan (lampshade) collar is recommended so he doesn't further traumatize his ear, which could enlarge the hematoma or make the sore larger.
Please let me know if you have any further questions.