Aw im so sorry for your loss I had some ducklings a while back and had my littlest one drown because of a mistake my uncle made when he was duck sitting them, he did not know ducklinigs cold not swim without being with their mothers. I was heart broken. Are you going to get any tests done to find out what happened just in case it is contagous?

Dont worry, it is not silly to get worked up about it, a pet is a pet, regardless of what it is.