Bucking..

So, my horse Hunter has a bit of a bucking problem. Recently he's been ok at the walk and trot but as soon as I ask him to canter or my other horse canters and he wants to go along he starts to buck almost every time. Anyone have suggestions for getting him to stop? The bucking isn't just a little buck here and there it's like a full out rodeo horse throw me on the ground buck.
Also, I don't like the one rein stop..that doesn't work and it also scares me. I've heard wayyyy too many horror stories of horses falling over with that.

I know this is probably a silly question. But have you checked his tack? Teeth and back ok?

No, it's not a silly question.
Yep, I check his tack every time I saddle him up. Vet says he's good to go! He had the problem a while back when I first started riding him... he was super-well behaved then all of a sudden he took off on a bucking fit on a trail ride one day. I was just leasing him from my 4-H leader at the time and I had just had ACL surgery and had just gotten the doctors ok to get back on him so she got scared and sent him to a trainer as he took off bucking every time I went to mount him after the fall. Well, he came back good but then I tore my other ACL and had to take more time off and then things got busy with school and stuff. I rode him quite a bit but not as much as I did in the beginning and he was pretty good. But then it started up again randomly..no trigger that I could find.
I'm in school an hour away from home so I don't get home real often to ride but when I do he's good a good part of the time but the cantering is a problem. I haven't had a lot of time to work on him with it and I'm not looking for a quick fix or anything..just things I can try when I get over there. (I'm goign tonight :) :) :))
He's 8 years old fyi.

Do you lunge him? Does he canter with no bucking while lunging?

If he's ok while lunging without tack, it might be a tack or back problem.

Yeah, I lunge him first. He bucks sometimes while lunging.
I have a hard time believeing it would be a tack problem. It's the same tack that has been used with him since the very beginning and there was never a problem then.
I think it's more of a laziness issue/doesn't want to do it kind of thing because he's figured out how to get me off when he doesn't want to do something. When he bucks me off I get right back on for just a little while to make sure he knows that that doesn't mean that he's done working. When he bucked me off at a show once my 4-H leader and I lunged him a lot to make him work but out on the trail it's kind of tough. I've started riding with a halter and lead rope on along with the bridle too though in case.
I don't think he "dislikes" me because he's extremely sweet and follows me around whenever I'm around...I don't know. Any ideas for what I can do when he starts bucking to make him stop? Or things to try on the ground to teach him not to do that??

This happened to me when I was a little girl. We bought this sweet QH mare and she used to be a perfect angel, then all the sudden she started throwing people off.

We found out the guy we bought him from went to jail for selling bad horses or something... I'm sure there was more to it but I was in 4th grade so I didn't really understand.

Maybe he has pain somewhere and something triggers it? Maybe him mis stepping or cantering hurts him.

Does he buck in both directions or just one?

Is there a change you could have a vet/chiro out to look at him?

Yeah he bucks whichever way. It really doesn't matter.
The vet has checked him and he's fine. I don't know. I will keep an eye out tomorrow when I ride him/take him out to see if I can notice anything.
Besides that any ideas on how to get him to stop? Just more miles?? Anything...? lol
Thank you Appy for all your input too! I'm not trying to shove your ideas to the side or anything!! Just trying to get all the info I can :)

Don't worry about it Rustic. I'm not really sure what to tell you to do.

Have you tried riding with a crop or a lunge whip and when he starts to buck to give him a tap?

How is he, when you ask him to canter with other horses around?

Well the last time it happened was the first time in a couple of years actually. He went through a good streak and now he's back to it again but anyway, the last time it happened my boyfriend and I were riding and he took off cantering and Hunter took off after him bucking before I could even try to stop him. He went straight from a trot to one stride of a canter then bucking fit. I haven't tried riding with a crop yet...Might be worth a shot. Should I just tap him on the rear or shoulder or what with it?