The odds of somebody bringing germs into your house and you actually catching them is slim to none. The virus is spread from feces and v*, mostly. So using a bathroom right after somebody who is sick has been in there with d* or v* is a risk, but somebody carrying the virus into your home and you then catcing it is very unlikely. I'm sure it's just anxiety. For us emets it is just anxiety 99% of the time haha You're not alone with your thoughts, I promise.
And, lower stomach pain is probably just gas or something like that. As far as i'm concerned, if you have a stomach bug or something, the pain or discomfort is in the upper area, like between your ribs. There are lots of none v*-connected reasons to upper stomach pain as well though, indigestion being one very common of them. You're fine, I promise