Hi all
I've noticed hex has been falling over a lot more than he should

it's like his back leg gives way and slips out from under him when he runs and turns a corner (not even running fast, sometimes just a trot) He just goes "flop" and gets up and runs off.
kinda like a little puppy falls over quite a bit but he's now over a year old.
Today when it happened he gave a very surprised sounding yelp - got straight back up and trotted off. He's not lame but he often paces or sort of trots with his front legs and canters with the back legs. If he does trot 'properly" he is even and steps out nicely.
He had hip X-rays when he was 4 month old and they looked crap - but they were positioned so badly it's hard to get any idea of if there is actually a problem. When he went to the ortho specialist for his elbow I got him to have a look at that X-ray and he said he wasn't concerned yet seeing as there was no signs of lameness and he had a feel of the hip and said it wasn't loose.
But now I'm wondering if this slipping over is a sign of HD?? My other GSD plays in the same area, runs hard and turns on a dime, she's never fallen like that.
This dog makes me worry so much, he is gonna be the death of me