Which leg is lame? -- no matter, a recurring lameness of any legs needs attention. While a
dislocationCongenital hip dislocation
Developmental dysplasia of the hip
Dislocation
Dislocation of the hip
Kneecap dislocation
Nursemaid’s elbow
Patellar dislocation is a possibility, cartilage chips, growth/growth plate abnormalities/trauma, muscle tears, nerve damage are also concerns. Most of these require prompt attention to provide the best therapy for recovery. If it's a dislocation, seeing your veterinarian ASAP will provide the best chance of the joint staying in place with treatment. The same can be said of most of the other problems. There are lots of disorders that can happen in a puppy. Only a few of them they out grow, while others require treatment. Your veterinarian will likely want to take xrays as well to be sure to provide your little boxer with the most appropriate care. There's a long life ahead of your little (getting bigger day by day) guy - so let us know how it goes.