That sounds like an ear hemotoma, basically a giant blood blister in the ear. Sometimes it is more allergy related and fluid other than blood. Google Ear Hemotoma.

 

Not sure you should drain it yourself. Lots of info on it on the inter web.

2 weeks ago, I thought our female had a hematoma in both ears. Luckily our vet was fully booked. By the next day, the swelling almost totally disappeared, but you could now see a distinct bite or sting inside each ear flap. Looked like a stigmata. No vet charge

 

I have one with a hematoma right now. Antibiotic cream, drain it twice a day, wait on it to scar down. Other option is cut & suture. No fun...

 

Very often a hematoma is kicked off via the dog scratching itself in response to ear mites; so it's worth checking the inside of his lug 'oles. Have a good sniff, and look for excessive amounts of dark wax. Wipe out with a damp tissue and check under a loupe for passengers and bloody spots. Some time back I stupidly let one of my boys go overtime with his Frontline and he picked mites up off other dogs on the shoot, so I'm pretty punctilious now especially after the Vets bill.

Eug

 

We had that problem with our last BLF, large ear flap hemotoma from shaking her head due to ear allergies.

Vet drained it, we changed her food, problem solved.