thanks for your concern...i thought about parasites because we do live on a lake, I hadnt mentioned it to my doctor, but i definately will..
I am so sorry for your family. I do not know much about this, all the thoughts that popped in my head have diarhea involved. My son had C. Diff. this summer, but diahrea is a major part of that, vomiting and cramping as well, but if they have no diahrea I don't think it could be that, also the smell of the poop is, well, it is unforgetable.
I have seen some posts about parasites, maybe they can look into that.
I wish I had more ideas, but hopefully posting will at least keep your issue near the top of the page.
Best of luck for your & your family's health, you will be in my prayers
Jessie