Yes it's very common in pregnancy (even though i didn't have it with my first).
But i took tums one time and haven't had it since. Either talk to you dr or of your insurance has a 24 hour nurse line, like mine does, call them.
Not totally sure, I heard its common in pregnancy. I have GERD which is an acid reflex disease, basically I get super bad heart burn. The doc explained it as stomach acid coming back up and hitting the esophagus causing the heartburn, not sure if its the same for people without GERD