Aww :'(. I'm sorry! Well, have you noticed any sugar-grain specks on her? It sounds like the behavior could be a disease called ick (also commonly spelt as ich.) This is were little parasites invade her :(. Oh and YES you need conditioner!!! That is *for sure* a problem!!! You can get it for...
Ok, well you need a bigger tank but I'm not even going to get into that right now.
It's more than likely swim bladder. Shelled peas help, and goldfish eat almost anything, so yeah, put in a cooked shelled pea. It should pass whatever holdin' it up through!
If that doesn't help, there isn't much...