Poor Daisy. She is so skinny.
I have heard of Exocrine Pancreatic Insufficiency. But that's the extent of it. My friends dog was diagnosed with it as a possibility of why she wouldn't gain weight. And she was having loose stool with some blood at times. The vet gave some meds (sorry I can't remember what) and it seemed to stop. They also perscribed a special food for her. The challenge was her family not feeding the dog human food and only feeding the special food.
Anyway, she has recently began to have the bowel issues again and once my friend can afford it she will have more extensive testing done on her. However, Tessa is only 4 years old and is obviously not as bad (skinny) as little Daisy.

I hope your son can get her what she needs. My friend took her dog to a vet specialists I recommended after they helped me with my cat.

Please keep us updated on sweet Daisy. I will keep her in my thoughts.