I hope this information is not too late for you to know.
I have been experiencing this exact same thing for three years. I get a fluttering sensation in the middle portion of my chest, this is immediately followed by what I would describe as a catch in my breath and at the same time forced me to a whopping cough to set things right again. I have been through all kind of tests, CXray and echocardiogram but it turns out to be negative and no one has been able to tell me.
On November 2014 my doctor finally found out that I have an AFib (Atrial Fibrillation), after they put me in a holster monitor for one month. My episodes (fluttering & irregular heart beat) could last up to 10 to 15 hours. I was then prescribed a medication called Amiodarone (Cordarone), 200mg, 1-tablet daily and my episodes was totally gone until the month of April 2015.
On May 2015, my episodes came back again. Again I went back to see my Cardiologist and she advised me of considering an ablation surgery and she referred me to an Electro physiologist. Needless to say, I winded up having an ablation surgery on July 17, 2015. I am now on my second week of recovery but I am still having short episodes. I have been advised by my Electro physiologist that it is normal to have these episodes after the ablation and it takes a period of six months to completely heal and eventually the episodes will go away. All I do now is to wait and see.