First trimester stomach troubles 🙈

How can you tell if you have a stomach bug or if it’s just an upset stomach from pregnancy? I know it’s a stupid question but I never had this with my first pregnancy and I’m worried in case it is a bug or something I ate and it effecting my baby. I haven’t thrown up, just my stomach feeling really off and hurts. This is the second day of feeling like this and I have work tomorrow 😳🤦🏻‍♀️