i went through all of your comments.I think i have same symptoms.let me explain my condition.
i am not feeling well for last 3 months.it started with dry cough lasted for like 2 months. i went to different doctors from general physician to pulmonologist. i was diagnosed with bronchitis.they put me on different medicines alot of medicines ..during all this i was on light diet.one day when i was trying to sleep my heart just start pounding .that was the first time so i was really scared.after few days i experienced the same thing with shortness of breath.now its been more than 2 weeks i guess now whenever i eat something shortness of breath gets worse or if i try to sleep.most of the time i am in this conditon.there is burning sensation and sometimes chest pain which shifts from left to right side randomly and also now i having cold feets most of the time even if temperature is normal.Now its happening everyday.i feel like i am always short of breath .i think its related with stomach and side effects of all those medicines because i was just having cough before and now its acidity ,shortness of breath ,chest pain etc.its been two days now i am again coughing.
plus xray they took were ok .(its been 2 month since those results)
Ecg and eco were also fine .(its been 1 month)
blood reports were also ok (2 months)

my observation: the cough problem which i was having before was also linked with stomach which they diagnosed as bronchitis and put me on alot of medicines .instead of helping those medicines make me more sick .now i cant even those foods which are recommended in acid reflux problems.and shortness of breath thats really awfull it feels like you are going to die ....i have to yawn forcefully to get a satisfying breath but sometime its also difficult due to chest tightness.

sorry for bad english .