My betta fish had fin rot and when I just thought I had cured it it came back ... But worse the fins are deteriorating super fast like I'll be in my room then go downstairs and there's a chunk missing with frayed brown edges (that's how I know it's fin rot not him and ail biting) I dosed the 1.7 gallon with 1.5 teaspoons of aq salt but the fins are still deteriorating and I just don't know what to do