Has she had a CT scan for MALs ( median arcuate ligament syndrome) also known as Dunbars disease and celiac compression syndrome. Very much underdiagnosed and considered to be a rare condition. The only cure and management is surgery. I have been dealing with this since childhood, 58 now. If I can help just one young person avoid life long suffering by getting the word out and sharing my experience , then it's to the good. Be a strong advocate for your child , be vigilant with research , insist on more scans , hopefully they will start looking outside of the " cookie cutter" diagnosis. Praying for a quick resolution!