Having Chest Pains

First off, I am going to see my physician, however not until Monday! I think I am going to worry constantly til then so I figured why not ask. I have been experiencing MINOR chest pains this last week. They are becoming more frequent and whenever I am at rest. My chest feels tight, and I feel like my heart is beating extremely fast/hard but when I take my pulse it is not. The pain is focused in the direct center of my chest, the breastbone. I notice it is also harder to breathe deeply whenever I feel this pain. The pain itself is just a discomfort and not very intense, it lasts about 20minutes. I am 19 and 5'3 110lbs, so I think my age or weight are not an issue. Has anyone experienced this before? I have considered heartburn, and watched what I eat this week, and yet it has worsened. Also I have not been working out or lifting this month. Also, I have consistent neck pains which give me headaches almost everyday, so I am always taking advil daily. & Thank you for so many responses!!