Yearlings dodgy joint- please help

[Muffin]

I have a welsh D yearlinmg colt who has a swollen hock,just the one,others fine. Had it for a month or so. Not lame on it but can be a bit 'mechanical' in his movement as I believe swelling restricts joint movement. Had 2 different vet practices look at him, one who wants to x ray then put cameras in, which is incredibly expensive.
The other vet said just to leave it as its his age.
Theres no pattern to the swelling,some days it goes up or down and it doesnt matter if hes been in or out for day.
We first noticed it when he'd been galloping round in a very muddy paddock,so wondering if hes strained something. Others say its just an irritated growth plate. Now considering trying box rest for a week or so and see if it goes. Has anyone had this problem with their youngsters?
Not keen on putting a baby on a course of bute as he doesnt seem in pain from it. He's also never been over weight as he had quite a poor start in life.

Any advice/past experiences much appreciated.

Thankyou

 

[minmax]

If I were you I would get it checked out, having bred my own next dressage horse, I have been gutted by him developing OCD. He is a hack at best, only 4!
He had a fat hock, I thought a strain or kick....then it went. It kept coming back and then the other one filled, he ended up down at Newmarket having both hocks and stifles looked at, cleaned up etc. He has a severe case of it, it has put me off breeding again and to be honest now I am left with a horse thats got no future I can't afford to buy another. When my current horse retires that will be it.

 

[AmyMay]

I'd be having the joint x-rayed and inspected thoroughly by the vets that recommended that cause of action.

 

[Cinnamontoast]

I'd look at x-rays. My friend's youngster (3) had a swollen leg and was on/off lame. He has issues with his tibial plates not yet having met and cannot do anything other than be walked inhand. It's a really good job the -rays were done or she would have started to work him. I think x-rays are the way forward if it doesn't improve very soon.