I was grocery shopping when I was paying all of a sudden got dizzy, and felt lighthead, like if a lot of pressure went to my head, alos started sweating, and my heart pounding fast like if I was running. I walked to my car came home and laid down and my heart was still beating fast now I feel real weak.

Maybe time to see a doctor?

You might have an inner ear infection, which can cause dizzyness. But, I agree with your other answer... please see a doctor. The inner ear usually doesn't cause a rapid heartbeat.

From the sound of your ID you are female? (Notice how little we know about someone online - we can't even see you)
Women have different heart attack symptoms from men. I actually would go to an ER if you don't have a family doctor to call right now. And I rarely suggest ERs to anyone.

Dehydration symptoms too, of course. I always assume that everyone knows the signs.