Betta is in 5G tank with a few MTS. Yesterday found ulcerated fuzzy spot on side of head. Began treating with Furan-2 and Kanaplex. This morning 25% w/c and another dose of Furan-2. Upon closer inspection, site looked ulcerated with long white fibers sticking out. Did a Methylene blue dip and sore immediately fell off. Now just ulcerated wound. Is this Columnaris? I’m continuing w/c and furan-2 and Kanaplex treatment. Also 2 methylene blue dips a day. I have a shrimp tank with lots of berried females so want to keep this away from them. Any ideas what it is? Suggestions? Thanks so much! Pics enclosed are after sore fell off. Weekly tank cleaning with Python and 50% water change. Parameters 0, 0, 20. Feed New Life Spectrum betta and frozen blood worms. Occasionally peas.