Food and vomiting

[Debbie and Belle]

Belle is just over 6 months and has been on the grain free acana regionals (she's had the lamb and duck, and the beef) and had been doing well with no diarrhea. Lately she has occasionally vomited whole pieces of food many many hours after eating. This happened on 2 isolated occasions. Saturday she vomited 3 times throughout the day and once in the middle of the night ( 2 times whole pieces and 2 times not). I took her to the vet today and they did an X-ray and saw a lot in her stomach when it should've been empty. The vet is not sure if she's having trouble digesting the food or if there is another issue. She is scheduled for a ultrasound and barium test tomorrow. Has anyone had any similar experience? I'm very worried about her.

[Nancy, Ned, Clancy, and Charlie]

He is 5 now so I can't really remember but probably only a few pounds.  He is not a big eater and he still weighs 27 or 28 pounds.