Wondering what exactly is wrong with me? Pain over left side of chest (over heart) ?

And I was told without an x ray by my symptoms alone that I had bronchitis by the local ER. I dont have a regular doctor to go to so thats my only option. I told her about the weird hollow cough, and how the pain over my heart seems to come and go.Also, my heart feels like its skipping and then beating fast and then goes back to normal. Im not sure what this is?? Its been affecting me so bad I cant really think about anything else. It is NOT anxiety, as I know what that is - I have suffered from that for years now. It is almost hard to breathe and I dont know how to make it better. The ER gave me azithromycin or something similar and Ventolin inhalor, which neither did anything for me. I took the entire dosage of the antibiotics, and used the inhalor as directed. I was a smoker, but I quit 3 weeks ago. I had been smoking for 15 years off and on. I am 25 years old. I hope to God its nothing bad but I am scared! Please, if you have any idea what this could be, elaborate! Thank you!