I'm 17, And A Female. Recently, For The Past 3

I'm 17, and a female. Recently, for the past 3 or so days, I've been getting a burning sensation in the middle of my chest. I have tried taking antacids, such as rolaids/tums, but it has done absolutely nothing for me. It just keeps coming back. I feel as though I have to burp, and when I try.. I bring up a frothy type of saliva or something like that. I have had some chest discomfort, but it was very light heaviness. Sometimes the burning sensation is accompanied with, before and after the discomfort. The discomfort is usually in my right side of my chest, and sometimes radiates into my shoulder.. Making it ache. I do remember, weeks ago.. While walking I would get a cramp in my right side. And I did have the burning sensation at times while that was happening. Lately it's just mostly been the burning sensation which is there every day now. What can this be? I do live with smokers.. And have my whole life. Could that be a factor?