Nice and easy. Maybe take a book and read by the horses stalls and just ignore him. Gently get closer and closer but he learns you aren't the one to be afraid of.
As for the head sensitivity, this is one of my favs to retrain
First off, you want to nit let the hear expect you to touch his head. Run your hand and rub where you can. After doing that fir a few minutes just run your hand ice, swift and smooth, over the ear and go back to rubbing the spots you cab touch. You di it fast enough that they don't even know what happened until you already did it. Don't make a Big deal out if it. Just one stroke and then retreat. Eventually you can do more and more.
I've never rehab-ed an abused horse before though. Just neglected ones. Posted via Mobile Device