My 7 month old boxer, "peyton" woke up yesterday morning and could not put pressure on his right leg. He would just lay down and have a very sad far-off look in his eyes. When I tried to get him to stand he stood on three legs and held the one up off of the ground. He also had trouble with the other hind leg slipping back trying to gain his balance. He back is also curved seemingly to compensate for that but he is so stiff that I can't help him move it back. I took him to the vet and they said he had a fever and the blood count showed a slight anemia but that didn't seem like a big link to the problem, because he hasn't eaten much. The vet also took xrays and said that cant see and problems on the film that would cause this. She mentioned it may be Panosteitis and said some dogs go through that in their growth stages and that there isn't really a cure, it just takes time. It troubles me because she wasn't very definitive about what the problem is and can only speculate based on lab results and xrays. Please help... my little puppy looks so sad, and I feel so helpless. Please respond...

Get them to check that is it not neospora infection or meningitis that is causing this,
Are your vets treating with antibiotics?
Are they referring for further tests as they should not leave him like this.

If your vet tells you that the tests suggested by Boxacrazy are unnecessary either insist that they are done or go to another vet and get a second opinion.  The symptoms may be nothing more than growing pains, but they could be an indicator of something serious. I wouldn't be happy until all possible avenues have been explored.