What could be the cause of my daughter's continuous vomiting?

[Tishbing]

I have a 7 yr old with tuberous sclerosis complex, severely affected in the brain (multiple growths, lesions, 3 SEGAs) with epilepsy well controlled through medication and keto diet. She is g-tube fed. She has a recently discovered heart murmur with mitral valve regurg, she has 40 growths in kidneys all less than 1 cm. she has been vomiting for 6 months with no respite. All blood tests come back normal (white counts, amylase, liver panel, metabolic panel, etc), upper GI showed no abnormalities. X-rays show she has some stool but not enough to cause this vomiting. Her blood pressure is now beginning to fluctuate to higher levels (from 90/70 -130/125) and her pulse becomes tachycardic during a vomiting episode (not before) to 220bpm. She tends to vomit more if moved. She is not tolerating full feeds and is beginning to lose weight. We are desperate for ideas. This is torture to my daughter and it's so painful to watch. When she vomits, it is more than just vomiting. It is a forceful expelling, abdomen becomes tense, red faced, etc but very little vomit unless right after a tube feed. GI believes that it's due to not passing stool every day but her bowel habits have never changed, especially not since this started. She has not had an impacted bowel (never has) nor has she had a distended or rigid abdomen which is why I am suspicious of GI's diagnosis of it being a result of stool. They've been pumping her full of laxatives and she's not getting better. If anything, when she poops she is sicker the next day. Stomach empties normally. Neuro says the vomiting is not related to any brain issues she has. She also has a sub-mucosal cleft palate, ear tubes, had an umbilical hernia repair as an infant.  Dear god, I am begging for ideas. Please help us. I need ideas because her doctors have no clue and I'm not sure they care because she isn't normal. I know that if she was a regular child able to tell them how much she is suffering, they'd try harder. Please please give me ideas for tests or ideas to have them be able to discount.

[JohnnyRocket244]

Have you been to see any Vascular Surgeons? There are some vein compression conditions that can cause all of the problems she is having and they are rarely diagnosed by doctors. Left renal vein compression (Nutcracker Syndrome) and SMA Syndrome that often happens with the Nutcracker where part of the duodenum gets compressed as well. Hope this helps and feel free to private message me if you want more info or have any questions.