Where is the pain/problem?

Hi Everyone,
Sorry I have posted so many threats on my guy. As some of you know, he trots in the back and canters in the front when he is cantering.
I am just trying to decide...
A) Call a Chiro
B) Call and take my guy to a lameness specialist

Here is a video, if you can help me tell where it is coming from, and which I should do.
Thanks

Definitely get the horse to a lameness specialist. While chiropractors can do amazing things, I'd want a vet to pinpoint exactly what the problem is, then perhaps collaborate with a chiro to treat the issue.
Definitely, without a doubt, a lameness workup would be best - something looks quite off in the hind end.. possibly the shoulder, too.

The video is really hard to see, it's kind of stuttery itself. First I thought left hind, but then I am not sure.

Hi, thank you for your reply.
I had just the local vet look at him a few months ago, and have had him on previcox since. She thought it was arthritis in his right hind. I just thought a chiro could help alot to help him carry him self better and hopefully solve the issue.

I will attach another video, but it is from 2011.

Here it is:
https://www.youtube.com/watch?v=yp84e7LCwAQ

Honestly, we are not qualified vets here. A video from 2011 isn't going to help, sorry. Your best bet is to get a vet out to run some tests, maybe do some blocks or x-rays, and let the professional help you with it.
The video is terribly choppy, hard to tell much other than yes, the horse looks off.
I'm sorry. I know lameness can be frustrating and you want many opinions, but the only opinion that is really going to matter right now is your vet's. Best of luck :)

ETA - Just watched the video from 2011... he does look very, very off. Honestly I don't think that running him around on the lunge or otherwise is going to help; you need a vet to come out and diagnose exactly what the problem is, and decide a treatment plan. He looks very, very uncomfortable and I really doubt working him in that condition is going to do anything good...

I know, I am just asking for peoples opinion.
He has been doing it for awhile, so it shows the same thing, but he was not believed to have hock pain the.
Sorry about the video quality
Thank you!

Just watched the video from 2011... he does look very, very off. Honestly I don't think that running him around on the lunge or otherwise is going to help; you need a vet to come out and diagnose exactly what the problem is, and decide a treatment plan. He looks very, very uncomfortable and I really doubt working him in that condition is going to do anything good... Looks like he's really trying to avoid putting strain on the left hind. If it were me, I'd put him on rest and not bother working him at all till a vet can see him.
Poor guy. Hope you get an answer.

He goes at that pace in the canter, where he is always switching his legs in the back. The vets in my area are not the best, so I guess I will find the specialist farther away.
Me too.