Totally agree with pheets’ comments – your horse is desperately trying to tell you something and its your job to figure out what it is.
It sounds a bit as if you might not be a very experienced horsewoman and your horse is running the show. Taking a few lessons with a good instructor who can look at the big picture as well as work a bit with your horse herself can help you pinpoint if the issues are you or your horse. The instructor should observe how you handle him from stall through tacking up, ground work, riding, cooling down and putting him up again. If your horse is all clear on the physical side, then you need to sort out if it’s aggressiveness or lack of confidence – the resulting behavior may look the same but addressing or fixing it is different.
You need to earn a horse’s respect to be the one in charge. It may be learning to be more assertive, or learning to send clearer signals. A horse charging you, whether from agressiveness or from lack of confidence (being on the lunge or in a round pen doesn’t allow a fearful horse to use his “flight” response), is dangerous and you need an experienced instructor/trainer to help you sort this out.
Patti Woodbury Kuvik