Great pics, hard to say what happened to her.

Do you have ticks?

Occasionaly I've seen hair loss around tick bites...

is there anyone around that area that has some sort of trough feeder or dumping feed close to an obsticle. when the deer are feeding could be rubbing its face at the same time.

Maybe he/she went in for surgery and they had to shave it there. It may have had a bet with another deer over something and lost. Could have had a birth mark taken off. Haha.

stuck it's nose in where it didn't belong lol

a itch,she will scratch up agianst a tree if she has an itch,and too much scratching will rip her fur off.

nice pic hard to say whats he has been into looks like a youg buck to me