How Can I Get My Dog To Stop Scratching Her Ear?

This dog needs to be examined by a veterinarian.  You are beyond treating at home if your dog's ear is "one big sore."  The underlying otic (ear) disease could be ear mites, infection (bacterial or yeast), fly strike, allergies, or a foreign body in the ear canal.  If these skin is as raw as it sounds this dog needs topical ear medications as well as systemic antibiotics and pain medication. 
This also needs to be treated before those flies that are so interested in your dogs ears lay eggs.  If this happens your dog will have maggots in the ear canal and surrounding ear pinnae.
Also aural hematomas (blood pockets between the skin and cartilage of the ear) are secondary complications that arise from broken blood vessels due to rubbing, itching, and scratching.  The treatment for this is surgery.  To avoid this complication work with your veterinarian to take care of this problem.

Your dog probably has ear mites.  You need to get some medicine and clean ears as good as the dog will let you.  Ear mites are very irritating and will cause the dog to scratch a til ears are raw and the dog will whimper while trying to scratch them.