Hi, I am Dr. Peter and would like to help.
1- Can you describe what are the signs your dog is showing?
2- How long has this been going on?
3- Do you know how it happened?
1- The lameness started after jumping up to greet your daughter or when he jumped off the couch?
2- Any swelling?
This could be related to a soft tissue injury (ligament, muscle or tendon), dislocation or fracture. What you could do is rest him; no jumping or running. Limit activity to urinate and defecate on a leash. Place cold compresses for 5-10 minutes 3-4 times a day. Start him on Buffered Aspirin 5-10mg per pound body weight every 12 hours with some food. Try not to keep on Aspirin for more than a week as it can cause gastric irritation. If no significant improvement in 2-3 days, consider having him checked by ASPCA or a shelter where they offer veterinary services at a lower cost.
If you have additional questions I will be glad to answer them.