I Am Currently 30 Weeks Pregnant & I Am Currently

I am currently 30 weeks pregnant & I am currently experiencing a sour stomach or acid reflux. This actually has become quite frequent these past two months & I want to know what can I take for it. Normally pepto bismol does the trick & I have taken it on separate occasions but I just recently read that I shouldn't since I am pregnant. Nothing else works that my doctor said I can take.. Like Tums & Zantac 75. Please let me know what I can do to relieve this.