ragged is just where it got snagged on something. It's nothing serious really, just something like the fish chewed himself or he got cut on the filter strainer or something of the sort.
Rot is a fungus, and a little more serious. I guess you'd say that ragged fin's treatment is like neosporin for a cut, rather than a disease killing med.
I think you should go a head and get the rot meds. If he don't get worse or better, then try parasite clear, or melafix/bettafix.
parasiteclear and mela fix both at walmart
It really wouldn't hurt to keep alittle of all of it around, just incase... edit: unless it expires, then jus get it when you need it