I would just right to MVR, as your doctor would surely have checked for this earlier in the pregnancy. Call his or her office and tell them what's going on, they may want to get you in to get checked out, or they may recommend something for the the heartburn, on a short term basis. One thing is certain, you're being this sick needs to be checked out.
Each pregnancy is different, and you can not always expect the same circumstances with each individual child. I was always told(wive's tale) that when you have very bad reflux or heartburn it means your baby will have a lot of hair.....I KEPT heartburn and reflux throughout my last 2 prehnancies and darn it....they were born with hair long enough to put braids in lol. Could you maybe have GERD? Indigestion? Also, make sure you keep an eye out on the acidity of your foods and drinks. Good luck to you!
If it doesn't get better, talk to your doctor about a prescription. I was given Prilosec throughout my pregnancy because if I didn't have it, I couldn't eat hardly at all or gain weight. I was assured that the acid reflux meds were safe.