Stomach virus or something else?

Monday night I started experiencing stomach pain... almost like nausea but like a dull pain that was uncomfortable. I've been taking my prescription Prevacid and Gaviscon, and that seems to be helping. I went to the doctors twice for this, and they said it's probably a virus. They said I am very gassy with a lot of air, and that I'm not constipated because I don't have much stool in me. I take Miralax a lot, but I haven't been taking it this week. I'm pretty sure it is a virus though, but my friend was saying something about Celiac disease. I had diarrhea, but not anymore. Any suggestions?