I have Labrador dog. It is 3 months old. Its back side legs are not working properly from last 1 week. But it is active. It walking 2 or 3 steps and fall down. Please suggest me any medicine. Is it well soon.

Take it to the VET... and do it now... in case its something treatible.

I agree he needs to see a vet, there are many things that could be going on.

No one can diagnose your dog online, or prescribe medication without knowing what's wrong, which is impossible online.

Your dog needs to see a vet, right away. That's the only answer to this. You won't find answers online. You really won't. Take your dog to a vet now!