Alka-seltzer while pregnant, right now????

I'm 2 1/2 months pregnant, completely fine. But I have a stomach ache. Its the kind of ache as if you haven't eaten forever, but I had dinner and a snack recently. Its been on and off all evening and night but I can't remember if I'm allowed to have alka selzter??? My book only mentions milk of magnesia, maalox, gelusil, and amphojel for stomach relief as antacids. I don't have any of these, ONLY alka-selzter. Please be clear, especially from any official lists. If its best for the baby I'll distract myself some other way.