Do I have a stomach virus?

So after I ate dinner today, after like a half hour, I got mild diarrhea (more just like loose stool, but I don't know, it seemed like diahrrea). I don't have any other symptoms, but I'm really afraid of getting sick because I have callbacks for a play tomorrow. I wash my hands as much as I can (ALWAYS before I eat, and I try to touch my face as little as possible), but you never know, something may have slipped in... May I have a stomach virus if I just had one loose bowel movement? Any answers would be appreciated, thank you.