Hi,I'm Dr Steve. From what you are secribing, he may have injured ligaments and/or tendons in his leg by overexercising and this couls cause his lameness
When this happens a dog instinctively reduces his exercise and after awhile, the rest makes the injured tissue feel better so they can get alng ok , then since they feel better they overdo it again and cuase more inflammation and pain. This is a very common problem. When I see dogs like this , one thing I do is x-ray the leg to be sure there aren't any small or hairline fractures. If I see none, then a prescribe antiinflammatory medicine like Metacam or Derramax. This along with consistent rest will often help substantially with the limping.
I hope this has helped. If it has would you please click the accept button so I may receive credit for my answer. Thank oyu and good luck. I will check later to see if you have more questions. PS don't give people antiinflammatory medicine as it can be very harmful to dogs.