Hi Katiethecupcake,
So sorry to hear that you're going through all of that. I know how hard it can be to live in fear of falling ill. It is, however, reality that people do sometimes get sick. You were correct in thinking that there could be a million reasons why that woman was sick - and you'll never know. I'm not sure where you live, but here in the south, I have heard of no such strain of stomach virus, and no one I know has come down with it. I would recommend taking a deep breath, and relaxing. Stress is proven to weaken your immune system, so please just relax and let it go.
It is healthy to talk about things that bother you - if your parents refuse to talk, I would advise talking to your school nurse, counsellor, a good friend, a friend's mom, etc. And, of course, we're all here to help!!
I hope you are able to relax and calm down. Chances are, you will not get sick.
Blessings,
DogLover8