Betta Fish: Please help with betta, not sure how to help.

The first 3 photos are when I first got him 6 months ago, the last 7 are from the past week.

I thought it might be fin rot, so I treated him with kanaplex 3 days last week, but he still has not gotten better.

I don’t have anything sharp. Any thoughts as to what could be wrong? Should I keep dosing with kanaplex every other day? How else can I help him?

Any help would be really appreciated.