Fruits and veggies are okay treats, but quail require a diet in large part PROTEIN to remain healthy. In the wild, all species that I'm aware of are insectivores—they eat mainly bugs.
Try mashed boiled eggs (theirs or a chicken's). Supplement that with a small portion of mealworms or other accessable bug to meet protein needs (but not too much, as they are high in fat). Depending on how long they'll be without pre-mixed feed, you might want to give them a multivitamin—ones for human kids will work if you can't find one for birds.
I'm not a professional, but that's what I'd do if I was in your spot.