Fishy tail grew back but looks different?

Ok so we bought our happy Blue at PetSmart. I know the bad rep these stores get but he was lonely, the others must have gotten sick and by gosh he called to me. Never thought I would be dishing all I did but he went from the store, to a 2.5 gal, to a 10 gal with filter and pump. Not one right after the other but within about a month.

He got sick shortly after, and his back tail suffered. I looked it up and started medicating with a little salt, then made the mistake (yes I am completely new to fish keeping) of putting some ghost shrimp with him because I was impulsive and thought they would be good tank mates.

Either they did not like him or they stressed him out more but then large chunks went missing from his beautiful fishy tail (he's supposedly a half moon) and out they came. A few months went by, and his tail grew back, but it doesn't look the same.

It looks ruffly, like the rose tail now, than he does a half moon. I don't quite remember him having a tail like that from the store.

Ii will post pictures if nobody objects, but has anyone heard of this? Is he still sick?