Should I take him to the vet?

I am currently sitting an 11 year old mutt who has chronic joint pain. He got rolled while playing with another dog I am watching and cried for around 30 seconds while holding his paw out. I notified his owners, iced his leg and have been giving him pain medication as well as CBD tablets (per the owners request). He is still favoring his leg after two days. I am periodically checking his arm for swelling etc., and all I can feel is a small cyst on the inside of his arm (because he is older I assume this isn't the issue). Anyone have advice? It is tough to watch a pup in pain.