Does anyone know what this is on my fur baby?

RyRy

My 10 year old lab/golden retriever mix has this on her back leg. I noticed it 2 months ago as a small bump and thought it was just a skin tag / wart. But it’s been growing and is now maybe the size of a nickel. I called our local vet but our appointment is still a ways out. It’s has me nervous and not sure if I should try another vet and get in sooner.

Has anyone ever seen this on their fur babies and know what it is?