Thanks again Tianna. I really appreciate the extra information.
What you're describing sounds like a proprioception deficit, which is not uncommon in geriatric dogs who have some degenerative issues (such as arthritis). Granted, this deficit happens more often with neurological issues, but I have seen it in some dogs with severe arthritis in their legs. It doesn't sounds like a side effect from the Deramaxx, since the half life on that is only 24 hours...meaning it only takes about 24 hours for all of the Deramaxx to be completely out of his system. Since he's been off for 3 days, I have a hard time thinking that it's the meds.
You can find more information here: http://www.petplace.com/dogs/proprioceptive-deficits-in-dogs/page1.aspx
The fact that since his proprioception is off (where her feet are in space) is always a key sign that there's something going on in his head or with the nerves to that parts of the body. Things like disc disorders or spondylosis (a gradual narrowing of the spine to the point where it pinches the nerves so the signal doesn't get to the legs) are the first things we'd look for if he were coming to our clinic.
I think that if this were my dog, I really do think that the next step would be an x-ray to rule out things like bulging discs or spondylosis. I know that they already did an x-ray, but from your description, it sounds like they focused more on his abdomen, rather than spine. Unfortunately in huskies, because they have such a long back, it's often where we find the problems.
If that comes back clear, then you may want to ask for a referral to a veterinary neurologist. These are the guys who deal with nerve issues day in and day out, and will be the most likely to figure out what is going on with your boy.
I hope this helps.