Re: Why can't I breath and cough and my heart races when I exercise???
Get an albuterol inhaler from your doctor and use it before workouts, if this is possible with your tachacardia. Start eating generally well and... well, honestly, I'm not sure what to say about how you should work out with heart issues like that. Sounds like you might possibly have a food/drug/supplement/etc. intolerance or allergy that's causing some additional issues. Those sound, literally, like textbook symptoms of an adverse drug reaction, actually.
You're not in great shape to work out hard, and I'd suggest looking around on these forums in particular for ways to get your body working better. (Liver flushing, etc.) A lot of people here, in my opinion (including myself) really don't particularly *need* to do what they're doing, but you definitely could use it.
Also, drink a lot of water, get your electrolytes up - that can only help things out.