I’m so sorry this is happening for your daughter. My Covid infection attached my GI system as well. My only suggestion is to try other providers if you have good medical options where you live. I went to three different Emergency Rooms for dehydration over about 10 days. I couldn’t eat anything and could barely take liquids . It was wasn’t until the third, where the GI doctor I consulted sees patients, that anyone took me seriously. I was admitted and they gave me potassium, magnesium, and antibiotics for a UTI they found. I am doing well now, about six weeks from original Covid infection. Hugs to your daughter.