best solution for freshwater ICH..??

[Llamarama]

hiya
noticed a bit of ick on my juvenile BP as well as my columbian shark about 35 days ago...removed carbon from filter and treated every day for 30 days with Jungle Ick cure liquid stuff at half dose due to my cory cats and my shark being sensitive...

30 days later everyone is fine...except my shark who is still COVERED in Ich no visible spots on anyone else so went out and purchased API ick cure liquid been using for 5 days and I think he's getting worse

any suggestions on what I can do for him?...we tried taking him out to QT and treat separately but he looked very unhappy and sick plus our version of QT is a plastic bucket as i have no extra tanks around but I'm sure this is going to start stressing the other fish sooner or later but he's not getting any better