yep, experienced similar (but not quite that heavy) symptoms earlier this year. turned out to be a panic attack. i started to feel dizzy during a course at university, and the more i (subconsciously) focused on it the worse it became, including numb feelings, disorientation, unability to speak properly etc.
i had my heart checked out after that, and it's fine except for a slight sinus tachycardia which i've had for a few years now, doc said it was fine though.
this shit can really fuck you up though. i honestly thought i was going to die.
best thing you can do is just not to worry about it - after having it checked out by a doctor obviously! the more you worry about it or experiencing it again the more likely you will actually experience it. panic attacks suck hard...