I'm so sorry that Maggie still isn't feeling better
. Maybe call the vet tech and see if the vet could prescribe something additional? Maybe Sucralfate (not sure if that would help)? Have you tried mashed potatoes yet...sometimes just straight carbs are soothing to the tummy, bc they absorb some of the nauseous juices, while also providing a quick energy source.
You're probably so stressed...please know I'm thinking of you and Maggie.