I am so sorry to hear about Diva. I have a few suggestions that I hope can help. A wonderful medicine that is used to coat the tummy is called sucralfate. It comes in tablet form but you dissolve it in a syringe (without needle) and then administer it from the syringe in liquid form. It's rather expensive but it does work well. It has to be given every 6-8 hours and an hour before meals to be effective. Getting Diva to eat is most important right now. When we had this problem, my vet suggested feeding anything that Garrett would eat. Nutrical is wonder to stimulate the appetite and provides calories, I would ask about that as well. The following is from Holistic Guide for a Healthy Dog by Wendy Volhard (any typos are mine):
One reciped I have used over the years to coax sick dogs back into eating is the following:
1/2 pound of beef or chicken livers
2 cups of willard or spring water
Put ingredients into a saucepan and bring everything to a boil. Stir the liver until cooked through, about four minutes. Take off the stove and cool. Put through a blender or food processor until it is a soupy mixture. If not soupy enough, just add more water.
Suck some of this mixture into a turkey baster. With your dog at your side, head parallel to the ground (elevating his head will cause gagging), gently squeeze a small amount of the mixture into the side of his mouth. Go slowly, and he will swallow. For a medium size dog about 1/2 cup of this mixture two to three times a day is sufficient. Liver is full of vitamins, minerals and amino acids, which help the healing process.
A supplement that works well with the mixture above according to the book is Seacure. It helps counteract nausea.
Once Diva regains some strength, I would recommend an endoscopy to find out what exactly is going on. Our thoughts are with you, paws crossed that Diva regains her strength and is on the mend soon. Please keep us posted.