A week ago, I noticed a lump on my Betta's side close to his front fin and his fins are looking webbed and stringy. I immediately changed the water and got a bottle of Bettafix from the store. It has been a week and it seems the lump has gotten worse and has even started getting pink blisters on it. His fins are also still webbed and stringy. He has recently stopped eating or is spitting out food. I try to change his water frequently, about once a week. What is wrong with him?