This may be a really dumb question but ................... how do you know it was vomit and not a stinky bm? Did you see her regurge it? 5 days seems like a long time especially since it was totally digested. Being malnurished can do a lot to a digestive tract which can lead to unusual abnormal stools. Just a thought. Either way I would wait 2 weeks then give her 1 mouse every 4 or so days for a while then try to switch her to rats.
If you smelled it... you'd know it wasn't a poop. It's awful!