RAPID HEARTBEAT followed by HOURS of LABORED SHALLOW BREATHING

male / 27
smoker (marijuana and cigarettes 10 years)
The first time i had this problem I worked out intensley with weights, then immediately took 3 hits of a marijuana joint,. within a minute, my already fast heartbeat went through the roof, then within 2 mins of that, I was left GASPING for air for hours, it was a very scary time i called ambulance and after a while i calmed down and breathing was ok enough for me to go home
.
This happened 3.5 months ago, and i quit cigs and marijuana after that cold turkey.

Now since then, i have been hacking out clear and yellow mucus numerous times a day on a daily basis. However, when i go to my doc to tell him and her about it, they listen to my lungs and send me for chest x rays and everything comes back normal and clear (then why do I hack out SO much clear and yellow mucus and have sinus congestion everyday????) anyways, today, after staying away from doing heavy demanding type jobs since the first episode, i had to cut the grass front and back,.. i finished the front and started on the back,. when all of a sudden i could felt my heart rate increase and then BAM it went through the roof , i stopped mowing the lawn and then within 2 minutes i was left almost gasping for air and could feel the tightness and congesting inside the center/lower area of my chest near diaphragm, this continued for hours , my breathing was shallow and erratic for hours. I strongly beleve this is happening because i have DEEP mucus stuck in my chest but the doctors look at me like im a fool when i say that and ignore me because the chest x rays show that i have clear lungs and when they listen to my lungs they are , as one doctor put it, "clearest lungs in the hospital". I dont know what to do, i cant work out anymore, i cant even mow the lawn,. whats wrong with me?  

so to summarize:

Demanding activity -> RAPID heartbeat for 5 minutes or so -> Labored/difficulty/shallow breathing for HOURS afterwords like lungs are working at 50%

[National Jewish Health]

First, it is very common for a person to have a productive cough worsen or a new productive cough to develop after smoking cessation and for the worsening to last as long as 6 to 12 months.  And, in most cases of bronchitis, the chest x-ray is clear.  Don't worry about it and continue to do your best to stick with the smoking cessation.

Sounds like you are having a very rapid heartbeat, called tachycardia, in both instances associated with exertion.  This abnormal rhythm should definitely be treatable and preventable in the future.  This may require ambulatory heart monitoring for 48 to 72 hours and, given the previous association with exertion, may require a treadmill exercise study to bring on the rapid rhythm.

[akuma4u]

just to add, i want to thank all the contributing doctors on this site for their wisdom , knowledge and help, it makes it convenient and easy for us to seek second opinions, this site was/is a great idea and I thank you for it.