Sensitive Ears

I have a 3yo that I've had from birth and worked with her from day one. I went to put her halter on few days ago and she flew back and wanted no parts of the halter going over her ears when they bent back. I rubbed them and tried to figure out what the heck is wrong since she never has done anything like that before. I see no bumbs or sores inside her ears and her mouth seems fine and teeth. Im at a lost since she's a relaxed horse and now throws her head and makes it a challenge if I hold her nose to her side and try. Taking the hlater off she's fine. Any ideas?? Thanks!

Ear infection? Bug bites?

Allergies or possibly her poll is out, if so you'll need a chiropractor to do an adjustment. Both our palamino's polls were out, one's jaw was out as well. The stallion had been extremely sensitive around his ears and after his adjustment he is far less but still isn't always cooperative when I am working around his ears on the left side. He will be adjusted again at least twice and then as needed.

I would check that is not anything medical, and then just work with her.
Get her used to touching, slowly get the halter over, and give her a treat, if she is good.
My horse is sensitive to water in his ears, I just run the hose slowly and carefully over his face and work toward the ears.
Good luck!