My female betta has developed a funny bump on her back. It happened once before a few weeks ago, but it was super small and quickly disappeared without me having to do anything. Now it's back, and two days ago, the size has doubled. The lump now bigger than her eyeball. I thought it might be a fungal infection, but the lump isn't fuzzy at all, it's just white (which could be due to her skin color, I'm not sure). I've had her for 1.5 years, and so far she's still eating well and is very active. I've been keeping her water clean as well. Can someone tell me what she might have and what I can do to treat her?
Here are some pictures of the lump on her back.