So I noticed that about 2 weeks ago my male betta had a little brownish red spot on it's back with a scale poking up. I went to the pet store and they gave me some antibiotics (API Bettafix) to treat him but I've noticed that the spot hasn't gone away and has become worse (it's now white with the scale deteriorating). He isn't acting any differently though he is a bit more lethargic (unsure if it's due to illness, winter or that he's 3 years old). I change the water completely about once every two weeks and use NutraFin AquaPlus as water treatment.
I've attached a picture of the spot. If anyone could help me I'd be so thankful and appreciative. I'm super concerned for him and would love for him to get better!
P.S If the photo isn't clear enough, let me know and I'll try and get a better shot.