I'm not sure if gas-x is safe to take. Best thing to do is to make sure your wife drinks plenty of water/fluids. Unfortunately gas and bloating are wonderful pregnancy symptoms that aren't likely to just go away. I find that yogurt helps me out when i'm overly bloated or constipated. The probiotics in yogurt help with digestion so it's worth a try.
Sorry to hear about the threatened miscarriage. Hope all works out for you and your wife and you'll have a happy and healthy baby.