My 3 year old filly keeps rubbing the middle of her mane out??. Any help or suggestions would be appreciated. It has been an ongoing problem.

Have you checked her for ticks?

Sweet itch has been insane this year. The gnats are terrible. Worse than the mosquitoes I believe.  There's little relief. Fans, fly spray and fly masks is all I can do. Started 2 of the worst on platinum skin & allergy in hope that it will ease some of the itching and using equiderma lotion on manes and tails. It contains neem oil in it and helps with repelling those nasty things. They also make a shampoo which Im wanting to try. Also adding extra flaxseed in their feed twice a day. 

My guy did that one year, I looked and tiny worms were coming from the bare spot, I wormed again and used MTG and I don't do fecal exams anymore and I worm.