Brief Answer:
Chylous is a strong possibility

Detailed Answer:
Hi.
Thanks for your query.
Read the history of the child of 13 carefully having Evan's syndrome and lymphocytic colitis and understood the concerns about the vomit that is cloudy white with pieces of white as you have explained and coconut odor...

As such a description fits only in the chyle that is lymphatic fluid, it is possible that that there is a collection of lymphatic vessels in esophagus or stomach that opens up from time to time to cause such a type of vomit.

Repeated upper GI Endoscopy with high suspicion alone can diagnosed this.
Another way is contrast study of the lymphatic system in this are.
MRI of the area can help if the Radiologist knows what to see for as he has to use the specific software for finding the cause.

Please get this done under the guidance of a Gastroenterologist, discussing the points I have mentioned to get the appropriate diagnosis and treatment.

I hope this answer helps you, please feel free to ask for further relevant queries if you feel that there is a gap of communication.

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Brief Answer:
Please give more details.

Detailed Answer:
Nice to know the MRE is negative, but it does not exclude all the possible causes and shows specifically the small intestines and not the stomach.
Noted the rest of the feedback you have given.
Since nothing specific is being found, further studies will be needed as explained above to further prove or rule-out the cause.
LUQ pain decreases after the vomiting and followed by persistent nausea indicates that there may be a reason to correlate.

I strongly feel on the same line as discussed above.
It would be very enthusiastic search by all that the cause may be found.
The vomiting sensation is sudden and without any warning, looks like diluted milk with grated cheese, resembles soap but the child has been observed and is not taking any such contents.
May I please know a few more things:
- Since when has this problem started?
- What is the frequency of such an attack?
- Since the vomitus has been subjected to lab testing, what is the report?
Please post the report if you have it.
- Since the family members have seen this, what is their opinion?
Can you post the photograph of the vomitus if available?

Since this is an atypical presentation, further detailed investigations are needed.

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Brief Answer:
Few more investigations

Detailed Answer:
Thanks for your feedback.
Pain in LUQ, unrelieved by NSAIDs and narcotics - 4 weeks - decreased over time - nausea and vomiting 2 weeks
pH on vomitus negative - May be coming from esophagus or the patient must be already on PPI or so.
Sweet smell: can not really explain the smell
Neg for Pancreatic enzymes - means not coming from the duodenum, difficult to say why is it tested for.
Temperature of sample cooler than the body temperature: does not take much time for any sample to get cooler once in contact with atmospheric air.
Attending and GI Doctors do not feel any problem: the different character of the vomitus is a concern and must be investigated.

Please ask them to tests the sample as per the composition of lymph and see if this matches or not.
COMPOSITIONOF LYMPH 1)Water: 94%, 2)Solids: 6%. The solid content found in the lymph are as follows: i)Proteins: Total protein content varies from-2.0-4.5%. Three varieties of proteins are found–albumin, globulin and fibrinogen. In addition to this, traces of prothrombin are also found. Fibrinogen content is very low. ii)Fats: In fasting condition fat content is low but after a fatty diet it may be 5.0-15%.

Also needed is the MRI/CT scan of the chest and upper abdomen in consultation of the Radiologist as this is a rare case and needs a thought of finding the cause.
Upper GI Endoscopy

I hope this answer helps you to get further information which may help in diagnosis and further management.
Of course the close observation of the child to be continued.

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