I am currently taking care of the office fish which is a betta. He is not doing so well lately. He seems to be eating less and swimming less. As of late, he's got a white lump growing on his tail. It's only getting larger. I'm quite worried. He is two years old and lives in a fairly small...

This is my grandma's Betta, and I just got here to find that he seems to have a lump on his upper tail? I tried to attach a picture, lets see if that works. It's wide and has white spots (doesn't look like the pictures of ich I saw online?) and the white is most noticeable on the one side and...