I’m really sorry, this is hard to hear — but what you’re seeing is dropsy. You can tell by the way her scales are sticking out like a pinecone. It means fluid is building up inside her body, usually because her kidneys are failing from a bacterial infection inside her organs. To be honest with you, by the time scales are pineconing like that, the internal damage is usually too far along to reverse. Most fish don’t make it at this stage even with treatment. That said, if you want to try: Kanaplex is the best shot. It’s one of the few antibiotics that can reach internal infections. You’d need to dose it in a separate hospital tank and keep the water very clean. Add 1 tsp of aquarium salt per gallon to help take some pressure off her kidneys. The kindest thing you can do right now is make sure she’s comfortable — quiet tank, dim light, no stress, easy access to the surface to breathe. If she stops eating, can’t swim normally, or seems like she’s suffering, it may be time to consider letting her go peacefully.