Betta Fish: Betta turning white

I posted about it already, so please, if you have questions – check my previous post. The

White streaks showed up overnight. I was afraid it was columnaris or graphite disease, but it's one week later and he's still doing fine besides the fact, that ge's a totally different color now 😐 The first picture is him now, the other picture is him a month ago.

I was suspecting a bacterial issue, because he's a chronic fin nipper.

If any of you have any ideas or suggestions, please let me know!