What Causes Pain In Breast And Sternum Along With Chronic Cough?

I am19 and I have recently been having a flip flop feeling as soon as I lay down.i have had episodes during the day where my heart rate will go above 140. I also have chest pains on the very far left of my breast and left side of sternum. This has lasted for 3 months with a chronic cough that produces a white or clear mucus. I do have acid reflux. The pains really ramped up after my second surgery which was a laparoscopic appendectomy I had that on February 16 . It also got worse after my egd which I had last week. I wake up feeling depressed and heart rate is racing . My doctor told me that I might have an overactive sympathetic system. I Am worried that something is severely wrong can you help me?