Heartburn & acid indegestion !!!!!!

Grim • I love being a phenomenal mommy ! <3 I am 20yrs old and I love my babies !(;
So I'm 37 wks & 3 days,What is the best otc medicine to take for heartburn & acid indegestion that with last all night? It seems I'm going to have this until I go into labor,lol 
It's irritating at times & it's hard to sleep as well. Help!!!!