My arabxqh mare

I resuced 2 horses a couple months ago but the mare I am having some problem with. I know it comes with trust, but i'm looking for newer/fresher ideas. My arabxqh, Macii ,is super headshy, shes allowing me to touch one ear and rub it but her other ear, i cant even get close to it or she jsut goes snakey. I'm doing TTouch right now, ive been slowly moving up her neck and doing small circles on her poll/neck area and she relaxs but once i get close to a horrible scar on her poll/ear area she flys right back and the whites of her eyes are showing. She was twitched with a large chain around her ears

Any ideas on how to help her with this situation? She's gotten much better, allows me to pet her, feed her, brush her and catch her, which she never used to let us do.

If you have any ideas please tell me. I'm open to anything. I'd like her to trust me before her foal is on the ground. Because I'd like to be there for the foaling incase something goes wrong.