RL horse acting weird

Okay so these past few weeks my RL horse, Hawke, has been much better behaved than usual. He's been more responsive to aids and has seemed to enjoy obeying me more. I was really happy about his better attitude......until day before yesterday. The workers at the barn we board at have been turning him out after dinner and we got there kind of late, so he was already out in the field. Normally (and everyone who works there can vouch for me) he comes running up to me out of the field (he even did this when he wasn't as well behaved), and was always the first tho come in when they bring all the horses in for food. Not this time. He wouldn't let me get anywhere near him :( I even brought a portion of food out in a little bucket to try to entice him. Nothing. So I ended up just leaning against the paddock fence to watch him. I tried a few more times and he still wouldn't let me get near him. The other horses had no problem with me. I finally managed to get a halter on him, but by that time we had to leave anyways.

Next day:
We decided to try again the next morning. When I was talking to the stable hands, they had encountered the same problem. Again, he's usually the first one out of the field, but he wouldn't come to them at all. While the other horses came up to them and had no problem being caught, Hawke stayed out in the field galloping in circles. It took them an hour to catch him. No one knows what's wrong with him. I was going to ride, so I tacked him up and took him to the outdoor arena. His best friend, Dusty was also being tacked up but was still in the barn. So I get on Hawke and he starts fighting me instantly. He moved away when I mounted, and wouldn't turn without quite a bit of effort, and his main goal was to get back into the barn with his best friend. When I prevented this, he reared. He has NEVER reared with me. EVER. he always makes sure I'm safe even when he's being a pain, but he reared for the first time nonetheless. We ended up going on a trail ride with Dusty and his owner, but just to make sure that he knew I was still in some semblance of control, I would stop and back him, and make him walk away from his friend every once in a while. Strangely enough, he was OK with it.

Everyone has noticed a sudden change in him these past few days, and we all have zero idea of what the problem is.

Are there any new horses at the barn? 

My gelding is extremely buddy sour so taking him from pasture mates is a pain. He never just flat out ignores me in the pasture though. He does act up when I'm riding him but only if he can see his pasture mates while I am riding. 

I'm honestly not sure what to think of this. Just try to figure out any and all changes that have happened? Even if they are very insignificant to you. 

Do you think there might be something wrong with his teeth?

My friend’s horse was almost doing the same thing and she called the vet. He did a thorough exam and found out his teeth were in bad shape. He had some teeth missing and some broken. Now he is the absolute sweetheart.

Strange my horse has been doing the same thing recently. He used to be super easy to catch and would walk right up to me when he noticed I was there, but now he runs off with the other horses. Eventually I catch him and he acts pretty much normal until the moment I tack him up. The ride starts out fine and all of a sudden he starts acting up, throwing his head and hopping around. I talked to my mom and the owner of the barn and she gave me a few explanations as to why he could be acting this way. The first thing she mentioned was that it might be his teeth that are bothering him or possibly his back is hurting him. Another was a change in bit while riding, but that doesn't quite explain his refusal to come out of the pasture. There's just so many possibilities that I can't decipher which one it could be. Anyways I hope that you can figure out the root of the problem, wish I could be of more help.

Did you change the bit or the saddle lately? Or maybe your tack fell down from the high or maybe your horse fell over with the sadle on? Many behavioral problems comes from tack problems, mostly saddles.

Thank you guys for your input. I'll have someone look at his teeth and ask the barn manager if anyone has been moved around in the pastures.