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Hello. Thanks for the question.
In a 10 month old large breed dog, my guess would be that you're dealing with growing pains. As the bones are growing and some growth plates are closing, they can have an intermittent lameness. These will usually resolve on their own over a few days. A soft tissue injury (sprain, strain) can also look like this and resolve on it's own.
One thing to rule out, would be HOD (hypertrophic osteodystrophy). HOD and Pan-osteitis are inflammatory conditions that will also cause a fever. I would check a rectal temperature to see if it's normal. Normal is 100-102. If > 103, then it's probably one of these inflammatory conditions. They are best treated with anti-inflammatory meds (Rimadyl or Prednisone). They are seen commonly in growing large breed dogs. They will eventually grow out of it, but meds can help make them comfortable until they resolve on their own.
I hope this helps, let me know if you have any other questions.