Edge of ears...
Are the insides of her ears red? Is she scratching her ears/head area a lot? Does she seem to shake her head a lot more than normal?
My baby had that problem about a year ago. We had blood splatters all over our walls from when she would shake her head. Our vet gave her trental to help with circulation and said this was a common problem for boxers. The trental did help, but I wasn't satisfied. To make a long story short, our situation has been long and frustrating, but we eventually took her to a vet dermatologist - she's highly allergic to dust mites. Now, all I have to give her is a weekly allergy shot (total cost of $39.00 per year). No more trying to guess what it was, no more special food, multiple meds or one more misdiagnosis. AND, I've got my baby back, happy and healthy!
My best advice - if you think it could be allergies, look for a vet dermatologist in your area - IT WILL SAVE YOU MONEY IN THE LONG RUN! When it comes to problems such as allergies, you would be shocked at how much your regular vet does NOT know. They jump the gun and want to give prednisone if they can't figure it out. I was worried about the money at first, but after hearing that the prednisone was taking years off my dog's life, I was furious, we had done everything in our power to help her - ripping out all of our carpet, installing hardwood, getting rid of all house plants, expensive special food, meds over $100 per month, vet appointments once a week, believe me - An allergy test @ $350 is nothing especially when it gave us the answers we needed and peace of mind.