Osteosarcoma?

Our 12 year old Havanese is still awaiting test results but possibly/likely has osteosarcoma. He has small moth like holes around his hind leg ankle. Not many maybe 5 or 6. Until a couple weeks ago he was totally fine. Then he developed a mild limp so we took him to our vet. She didn’t mention that until the radiologist did and we’ve been to a specialist. They said there’s a chance it’s this specific infection. Until tonight he was completely normal just the mild limp. Tonight he started holding his leg up more and can’t seem to calm down. I called the emergency clinic and he’s had as much medication as he can handle tonight. I’m not sure what to do. Waiting for the results is agonizing. My wife and I are emotional wrecks and balling our eyes out all week. I just want our boy to be ok