D..
If I were you, I'd go get your family tested for strep. Sometimes strep causes stomach problems that sound like you are experiencing. Just because the kids feel better doesn't mean that they don't still have it.
This happened to my son when he was preparing for exams at college. When he got home, I took him in for his yearly physical, and I told the doctor about that. It had been a few weeks since he was feeling so bad. The doctor took a strep test and he tested POSITIVE. I was so grateful to this doctor. My son was leaving in a week to be an RA for a group of junior high students for a 3 week academic camp. Can you imagine him carrying strep around all these kids!?
Good luck and feel better soon!