Fungus or columnaris on my betta? please help!

My CT male betta have this white fuzzy string-like white thing on his front pelvic fin and also a little on the tips of his anal fin. it's like stringy and fuzzy and cottony looking. I thought it could be fungus so i bought pimafix (antifungal fish remedy, all natural extract of west indian bay tree). after 2 days, the white stringy stuff is still there and it hasn't gotten any smaller. i think it might even have gotten abit longer... i realize that some people call pimafix an herbal remedy instead of an actual medicine, but the closest petsmart doesn't sell any other fungal medicine other than rid ich but that's more for ich.

my betta doesn't have this white substance anywhere else other than the ends of his tail, but i want him as healthy as he was. The stuff covers the length of his front fin.  i believe the stuff fell off his hind fins once and it looks like a feather fluff but in a string horseshoe shape.

could it be columnaris because it is white? but it hasn't appeared on its usual popular spots like mouth, etc. plus its already been a week and this fluff doesn't seem to be progressing very quickly.

So, i'm still leaning towards fungus. See attached pictures and please please tell me what i should do.
i'm thinking of switching to rid ich+ because i think the bottle does say it treats fungus.
Also, my fish doesn't seem to like the pimafix all that much because he gets abit erratic when i put a drop in.

i feel like he's miserable :( and so please if anyone know what this is. whether its fungal, parasite, bacteria,ich, columnaris? and if rid ich+ is right for me.

i do use water condioner and abit of seasalt everytime i do a water change, just incase you were wondering. the tank is guaranteed very clean so please look at the picture and tell me what that is!

[rowsfame]

he's not blowing bubbles anymore and he seems more depressed than ever :(
the white stuff persists and i do a 25% water change every 2 days to try and remove bits of the stuff. if i stir up the water there will be bits of white floating and settling down. what IS it?
Also i noticed when i didn't do a water change for 4 days there was a fine layer of fuzziness all over my fake silk plant. i didn't see it until i shone a light over it and it was scarrryyy.