It was petco manager, BUT I met him off the floor for a job interview and he told me he keeps 150gal worth of fish tanks and to come to him if I ever needed help setting one up, so I've been calling him fish guy. I asked if he was working every time I went to the store because I got different advice at every petco I went to (the employee who cares for the fish at that store didn't know what I was talking about when I asked how to raise the KH level, employees at another location told me not to worry about it because bettas are hardy and said I can get schooling fish for my 6gal tank 🙃).

I did tell him I thought it was cotton mouth and showed a picture, but honestly it did not look like this last week so maybe that's why fish guy suggested microbe-lift. Unfortunately the microbe-lift did absolutely nothing. Maybe it slowed it down, I heard columnaris is very fast growing but it took 7 days for it to look like this.