If he is eating some food you should treat with either new life spectrum hex shield food. Or use your own pellets that he likes and soak them in Epson salt solution.
https://www.monsterfishkeepers.com/forums/threads/treating-hexamita-aka-spironucleus.339362/
Any odd looking poops?
I haven't seen him poop in a few days, but that's also due to the fact that I'm out and about most of the day and really only spend tons of time with my fish at night.