It's great that your injured betta is improving! I think, even only after about 3 days, my betta's fins are becoming less black and he's becoming more active. That could just be because I just did a water change.....
EDIT: I'm just curious, what time is it where you guys are? When I go on I often don't understand why hardly any people are online. Then I remember time difference. Isn't it like 5 hours earlier in New York than London?
It's 2:22 p.m. over here. I'm in the NY time zone, I think. And I'm glad to hear about your fishy!
Just in case in need to do salt treatment, do you keep the fish in the QT for the whole 5 days or whatever, or is it like a "salt bath" where you put the fish in for a matter of minutes?
Also, I was just told by someone, do I need to do more than 33% water changes once a week (gravel siphon), in a 9 Gallon tank with a filter and a few live plants? I currently only have Suzuki in there but I may add some shrimp.