5yr old very awful stomach problems

Hello I am here in seach of help. My 5 year old daughter started vomiting about 1 month ago,  since then she vomits every other day, as she puts food in her stomach it hurts. Sometimes she vomits just mucus and bile, sometimes its undigested food that she ate several hours earlier, one example is she had grape juice one night at 7pm and when she vomited at 4pm the next day the grape juice was still there. She had blood work done and they ruled out a stomach virus and bacteria as well as Ceilac. She had an upper GI done and the person who preformed it said her stomach looks fine and they don't know what she is vomiting so much. I took her to the dr today, she has lost 6 pounds, he thinks that she has a strecthed bowel and that she might be getting impacted. He put her on miralax and I am suppoed to wait 2 to 3 weeks to call him back. She has never had a "pooping" issue and up until recently she has always had regular BM's regularly. She does have reflux and Dysphagia. Here is a list of her symptoms: Chronic vomiting, Weight Loss, Stomach aches, lack of energy (just recently)
Please if someone has seen something like this or has experienced this please help me figure out what is wrong with my daughter.

[boron]

There was a father of one 5 year old here on the forum, saying that his 5 year old vomits a lot, since they want to put him in the daily care center. Do you think, your daughter protests against something, or asks for attention?

Pain after the meal is characteristic for gallbladder disease (ultrasound, HIDA scan) and  aneurism (aneurysm) of abdominal aorta (rare).

[CalGal]

Please ask your doc to consider either gallbladder issues (yes, it can happen in a child) and check with ultrasound and HIDA scan with CCK injection, or look into gastroparesis. A gastric emptying scan can be done to check for that possibility.

If the upper GI was a barium form, you should also consider the possibility of having an EGD done.

Is there any celiac problem in your family anywhere? If she was checked via blood test, it's not the most reliable test in the world. And if you've got relatives with celiac, try a gluten-free diet just to see if it helps. There are many people with 'silent celiac' who are negative on the blood tests only to find out later that they actually have a gluten problem.