I think you need to see a good Gastroenterologist (GI doctor).
Summer camps can expose you to contaminated water. Giardia
https://health.google.com/health/ref/Giardiasis
you don't need all the symptoms to have this...and it often goes dormant and recurs.
It is diagnosed by a stool sample.
Also investigate gluten intolerance... which is common also.
It can cause nausea and other symptoms.
Also H. pylori, can cause stomach ulcers. A positive response to Pepto, suggests this too. So I do think you need to see the appropriate doctor, to find your answer.
__________________
All truths are easy to understand once they are discovered; the point is to discover them.-- Galileo Galilei
************************************
.
Weezie looking at petunias 8.25.2017
****************************
These forums are for mutual support and information sharing only. The forums are not a substitute for medical advice, diagnosis or treatment provided by a qualified health care provider. Always consult your doctor before trying anything you read here.