Also, I had a friend who was experiencing similar symptoms and he thought he was on the verge of having a heart attack, which only perpetuated the panic attacks he was having!
His doc gave him an actual heart monitor type instrument, you wrap it around your bicep and record your blood pressure. We were in another state one time and hadn't smoked in damn near 2 months, I had my sister send me some great weed via USPS, it arrived shortly after my bday and 20 minutes before we sparked it I made sure to mention to him "OK, this is gonna be some strong shit, especially since we've been sober for 2 months! Don't overdo it, don't worry about dying!", we smoke for 20 minutes and I reiterate, "don't overdo it!", he says he's fine, then 15 minutes later he's grabbing his heart monitor and telling me "dude! We HAVE TO go to the emergency room!!!", I tell him, "OK, but your mom is going to find out about this if we do that, are you sure?". I drive there, and he takes his reading again in the parking lot, turns out, he had the shit upside down the ENTIRE TIME!!! LMFAO! After about 10 minutes, he finally calms down and we drive back home, but damn, straight up hypochondriac! I'll remember that til I die...