The bulge on her ear is probably a hemotoma. That's when blood fills up inside their skin. If she has been itching her ears, and SHAKING her head, she can give herself a hemotoma. Give it a couple days and it may self dissolve. If not, get her to the vet to have it lanced. Been a dog groomer and have had cockers all my life. Good luck.
It sounds like a ear hematoma, and if that is what it is it can be caused by a number of things but most of the time it is caused by dogs that will shake there head a lot. Most of the time the treatment option is do have the vet drain it by using a biobsy punch after it is drained they will put a few sutures in it to get the ear to adhere back together, they may also try to drain it with just a synringe but with that method it is likely to return. Ear mites would make a dog shake there head too. For the flea medicine that you get over the counter can be dangerous to your pet, I have seen to many cases come in having seizures from using that stuff.
The swelling in your dog's ear has nothing to do with mites. She has an ear hematoma, which is defined as the ear flap veins breaking and causing a buildup of blood in that area. It is EXTREMELY painful for the dog. And there is no home remedy. She MUST have it surgically drained. Please take her to be treated as soon as you can beg or borrow money to do so. Blessings - Blu