Betta Fish: what do i do? what’s wrong with her?

i got my girl vexa maybe a month ago? my tank was already cycled and water parameters are literally perfect. she seems to have developed swim bladder disease and is struggling to swim correctly. i’ve fasted her for almost a week but i don’t want to starve her, she also just refuses food. i don’t know what to do or whether i should euthanize her or not. i’m worried and i need help.