Oh dear. rainbow. Would you mind posting what she looks like, (I know, ) and maybe your water stats and the other tankmantes, as well as hw old she is, and we can help you figure out what happened.
i cant send a pic i havent got a cable i'v had her for 7 months (i got her from my LFS and she was fully grown then) she wasnt in a tank with anyone else i took her out when i spotted the spot on her nose.last night when i looked at her she looked yellow,well she was a yellowy coloured guppy anyway but she looked really yellow
i flushed her about an hour ago one side of her had gone a yellowy browny colour and her scales had came up i think she still had some babies inside her aswell