Eosinophilic Panosteitis:

"Pano" (or growing pains) is a disease that resolves without, or in spite of, treatment!
It is generally rapid-growing giant males that are affected.
Food too rich in protein and calcium may provoke the problem.
A healthy puppy suddenly develops an acute and painful lameness with no known history of trauma.
The lameness often shifts from one limb to another. It is easily diagnosed by veterinarians.
Anti-inflammatory drugs may be prescribed, and attempts to slow the rate of growth of the puppy are usually recommended. The good news is that pano is self-limiting and does not seem to result in
any long-term damage.