Zoe's illness-- an eitology? Please?

So Zoe's had a cough since right after Halloween. She's been to the doctor, taken albuterol, antibiotics and finally, prednisone (a coriticosteroid) to help her beat the cough. Suddenly, she's developed so really weird nighttime stomach ache. She said she felt like she wanted to throw up but couldn't. She writhed on the bathroom floor for an hour, got up and went back to bed, then got up again another hour later. The next day we called the doctor's office. The nurse said it was probably her sinuses, dripping into her stomach and her stomach was rebelling from all the mucus that now lay therein. That sounded sort of plausible even though she always has a cold and has never had a stomach ache accompanying.
The next day, she's 100% fine. Running, bike riding, movie-going, regular kid.
That night, more writhing. More chants of, my tummy, my tummy. No sleeping. More Erik and I saying, poor Z. I'm so sorry and rubbing her back and feeling totally helpless.
Two nights later, on Saturday night, we called the triage nurse, having been on the verge of taking her to the ER. That nurse said, if she's not coughing up blood or bile, if she can walk without clutching her stomach, and if it doesn't hurt on the right side (appendix) then she doesn't need to go to the hospital. Stomach things are weird, she said.
The next day, she's 100% fine. Running, bike riding, movie-going, regular kid.
That night, more writhing. More chants of, my tummy, my tummy. No sleeping. More Erik and I saying, poor Z. I'm so sorry and rubbing her back and feeling totally helpless.
Last night, more writhing. Less sleeping. Max decided 45 minute-stints of sleep were sufficient. I think I called him "numb nuts" as a rocked him to sleep--in a nice voice but these are the words that escape my mouth when I haven't slept in six nights.
Her stomach actually hurts now (in the day time!). We're more, "I know your stomach" hurts now. And more "yeah, stomach things are weird." Also, we've cut out all milk-products on the off-chance they're mucus-making or lactose-intolerable. But as Zoe says, "It doesn't help. Nothing helps. It just hurts."
We're also on our way to the doctor in a couple hours. But here's my guess what the doctor will say: She says, "it's a virus. Stomach things are weird." Or, at the other end of the spectrum, the battery of tests begins with an endoscopy and ends with a colonoscopy and has some CT scans in the middle.
So if you guys haven any ideas before the battery of tests begins, then let me know. Also, I don't think she's contagious. Max nor Erik nor I have any stomach pain as far as I can tell but if we did contage you, I'm sorry in advance and I hope that you sleep again one day.