I had constant heartburn and acid reflux for first pregnancy. I was advice to eat in small meals, drink water in between meals, no caffeine, no spicy food. When this happened often I requested for cooling gel which has been prescribed and I applied every morning. There are some that recommend Gaviscon but I have never been taking it through the pregnancy. Hope this helps.
Try walking around for 10-15 mins after each meal. Don’t sit down straight away. I stop getting heartburn since I try doing this. I have also consulted my gynae and get some prescription for heartburn to standby too.