Anyone had/have a senior dog?

I know this isn't a vet sight, but I've been searching for answers all night and can't find anything. I will be calling for a vet appointment tomorrow, but I want to be prepared if there will be bad news. I own a 10-11 year old blue heeler mutt mix. He has arthritis that we have been working on getting medicine for. He was also diagnosed with a heart murmur back in August. They said it was very small and shouldn't be a problem for a while. But lately he has been throwing up. He was just sleeping and woke up and started vomiting. Does anyone have any idea what could cause it or know of a site or something I can go to to do more research. Thank you very much for any help. I'm just super worried about him.