My dog's limping for 3 days, no swelling, but still playing. Should I worry?

Thank you for using Petco Pet Education Center, formerly Petcoach! From the pictures I don’t see anything abnormal. But if it has been 3 days and he is still limping then he is painful somewhere. In a younger dog it could be from growing but they could still have small fractures without swelling. I recommend taking Goliath to a vet where they can do a full physical exam and check for pain in the bones or joints. There could be an issue higher up in the limb or even in the neck causing the limp. The vet may need xrays to look at the bones and joints. If anything, they can prescribe Goliath some medications to alleviate his pain and get him comfortable again. I wouldn’t give anything over the counter as there isn’t anything safe for dogs. And until you can get him to the vet I wouldn’t encourage any running or jumping. Good luck and kisses to Goliath!