This morning an appointment opened up at the gastroenterologist! After paying our 28 day late health insurance (we were in the process of switching but Stella was denied, it is another long story) I took Stella in to see the doctor and find out what could possibly be wrong with her.
I have spent countless hours online looking into so many problems and worrying about what could possibly be making Stella's tummy so upset. I am happy to say that after visiting with the doctor (who listened a lot and was truly a wonderful doctor), we have a course of action and 3 steps to follow to figure this thing out.

First things first, Stella is going to stop the Prevacid--it was showing no real benefit and is probably limiting her digestion. Next, I am adding a pre-digested protein (called Eo28, sounds yummy huh?) to her diet and after a few days we should know if her tummy can tolerate this addition. If so the next step would be to add in meat proteins and go on from there.
If this doesn't work the doctor will put Stella on a prescription enzyme to aid in digestion, then lastly a scope and biopsies of her esophagus and stomach to diagnose what could possibly be some scary things. I am hoping it doesn't come to that.
I will keep everyone posted!