First post. Need advice on my backyard friends.

[Fluffy]

Our favorite one year old grey squirrel has just passed. A few weeks ago he was limping from a small bump on this front leg. That resolved, but shortly after
he developed one on his tail. He became lethargic within a few days. We trapped him to bring him to a vet, but he died overnight. Now I am wondering what
killed a healthy one year old. He shared a den with his Mom and a new brood....Help

[squirrelfriend]

He might of been attacked by an animal or fell from a tree. I can’t see the bumps. The tail looks bloody.