Those were the problem... hmm she look weak..
Do setup special quarantine tank for her Alberto, i guess the tank u used to give her eat it possible to use as quarantine tank. Pls give her more O2 Alberto, but don't too much aeration, if possible put some healthy feeder fish or small shrimp for her to look after. You don't need another sad news man!! i hope u got O2 pump overthere Alberto. get some filtration for the tank and maybe changer 15% water everyday... just my opinion.. you know wut the best for her man.