Zantac question

Dr
Thinking about asking for this from my DR next appt. tums is suddenly starting to not work and even the smallest things are setting me off. (4 cranberries made me miserable for 4 hours! Ugh! 😡) I'm just wondering how it's taken. Like do you take one a day or do you take one with a meal? Is it like tums where you take it whenever? How many have to be taken and how often? 
Also, for those Zantac works for are you eating a normal diet again or do you still have to avoid the foods that set you off? 
And last but not least, what side effects has it caused you if any? 
These next nine weeks would be soooo much better if I could just eat!