Stubborn horse?

A trainer will only solve the problem temporarily unless they train you too. A "trained" horse in the wrong hands ends up in a disaster. Not to say that you're a bad handler but there's clearly been somethings that you hadn't picked up on until it was too late. Be sure that you aren't hanging on her mouth when she stops. Most horses rear because they have no release in another direction, so they go up. Stick her back on the longe line and see what happens without a rider. Does she walk trot and canter without objection or does she give you the same problem. Do this both with and without tack. Maybe back off on serious work for a while. I don't know how often you ride but some horses aren't a fan of serious work. She may not mentally be ready. Just get on and walk her on a loose rein for a few rides. Maybe trot a little with minimal contact. Seek help from a trusted riding instructor though, if they suggest a trainer, go from there.

She has a ton of bad habits. In your place, I'd find a trainer, and leave her with that trainer at least three months. She's what is called a "bad actor", and these horses are just a true pain. I never had one, but I had a student or two who did. And there was no way I was going to get on these horses to try to straighten them out.

What a trainer will likely do is put her in a surcingle, and start over, doing ground work, with a head set, all of that stuff. Then put a rider on, but with the trainer still calling the shots. Next, and still in the round ring, a trainer on her, asking her to do what she had learned by being driven from the ground. I suspect this was never done with this horse, and that is why you are having problems.

At this point, she is beyond your capabilities. Any horse that is rearing, stopping, etc., isn't truly broke.

So you begin with her at step one, with learning from the ground.

Sounds like she's taking the **** out of you it means you are NOT firm enough with her (not leading !)

what you need to do is the "join-up" or get someone to do it for you and establish your self as leader (Alpha)

and she the follower then no more problems!! NOTE: DO NOT use a whip on her you'll only make matters

worse!!

Many times these little fits start with the horse in pain, especially back or wither pain. A young horses body and back especially change a TON as they mature and get fit. A saddle that fit well is in 6 months often completely out of whack. So I would rule out her back giving her issues. I had a horse like this and two visits from the chiro fixed his issue 100% along with a better saddle.

Or, she could be developing a truly bad habit and you have to seriously nip it in the bud with the help of coaching and support. My philosophy for these kinds of infractions is not to "get after" a horse because this often escalates into an argument and a pissy attitude but to "get in and get out" -- meaning spank them once as hard as you can with every ounce of hutzpa you can muster and then ride on like nothing happened. You choose the worst things first to correct (not respecting the forward cue of your leg for example because you desperately need this especially if she is rearing--spank just behind your ignored leg cue). You also have to be very generous with your praise so it is super clear to her what is good vs. bad. If you spank her like you mean it, she will avoid the behavior that gets her spanked -- but only as long as she knows there is softness and an easygoing lightness from you when she behaves. She has to have something to work FOR and not just avoid. You have to ride her like you expect her to be great and then have the stick (not you--the stick) spank hell out of her if she misbehaves.

I agree with Judy. Eliminate the cause as a pinching saddle or even wolf teeth...

I agree, she is becoming dangerous and you need to face that. Get somebody to work with her before you get seriously injured.