Hi Adz,
I studied lightning as part of the electrical safety component of my engineering degree. As mentioned before, lightning has a current distribution. From what you described, it sounds like you received peripheral current through your body. It seems that you were 'struck by lightning', but didn't get the worst of it. Also, when lightning strikes the earth, the charge has to spread through the ground, often resulting in ground currents over an area wider than the conduction path through the air (depends on local conductivity of the ground).
The peak current can cause severe burns, and heart failure. From what you described of your chest sensations, I'm guessing you experienced some muscular seizure in your heart. The current could well have temporarily disrupted the electrical activity in your brain as well.
Sorry to hear about all this, and hope all is well for you.
Oli
