I had this for like a week last week, it's settled now. I tried tums but they were crap, a glass of water was basically just as effective...! But there are loads of safe for pregnancy heartburn remedies you can buy in supermarkets and pharmacies. I think it's calcium carbonate you want (with the bonus of the extra calcium they give you).
Some people say milk helps them and some say it makes it worse! Personally I find it helps, you could try that. Also obviously stay upright as much as possible after meals, and don't eat spicy or fatty foods or huge meals. Heartburn is no joke, it can be really painful! Told DH last week I felt like I'd been sucking acid out of batteries 😳