He had a lameness exam in Jan (due to him partially pulling his shoe, then stepping back down on the shoe and driving the front clip into his hoof wall.) The vet vet said she couldn't do a lameness exam on a horse that isn't lame... I trust my farrier with my horses feet almost more than my vet. We've been using him for 13+ years and has always been spot on. He is the farrier for our vet who specializes in leg and hoof stuff, and is recommended by the other few vets we have as well.
Monroe does have an old bow from when he raced, but it has never been a problem. He's never been lame in the 9 years I have had him (except when he's had reason to, like trying to play with his neighbor and puncturing his knee instead). If if were a chronic pain, wouldn't it show every time I jumped him? And wouldn't he eventually start backing off the jumps?
My instructor tells me the basic things- quiet my seat, be soft with my hands, look to whatever direction I want to turn and SIT UP once he lands and starts being silly! The only other thing I can think of is it's a residual problem. Like I said, I had a very driving seat right before the jump (which would cause the squirrely-ness a few strides out). I took a long break (thanks to pregnancy/child rearing) and am now getting back into serious training. My seat is much quieter now, but maybe he still anticipates it? IDK...I am not an aggressive rider, I do not carry a crop (he doesn't stop, so I have no need for it) and I do wear spurs, but they are the tiny "humane" nubs that I only use when he get's lazy. I ride him in a slow twist snaffle but don't hang on his face or anything...the only time I grab at him is when he's throwing his head around to buck.
Again, if it were a pain issue wouldn't he have the reaction every time he jumped? He only does it when he knocks a rail when we are at home with me riding.