Why do I get dizzy/light-headed for days after a panic attack?

I've come across this before but I want to see if I'm not alone. Sometimes, though not often, when I have a panic attack, I wake up the next day feeling light headed, like there's a bubble in my head or there's an elastic band around it. It doesn't hurt, but it's uncomfortable and makes me derealize a little. When I walk or even sit upright, it gets worse, it only seems to soothe when I lay down.

It's day three after the panic attack and it's still with me, though not quite as bad as it was the first day, I suppose. It's just scary and when I focus on it too much, I begin panicking again.

I don't really know how to help it.