It will pass and you'll feel better soon. Stand up slowly. Sip some cold water. Splash a little on your face to send some extra blood to your brain. Sit or lay back down. Get comfy. Breathe deep and easy. Ride the fucker out. You have the skills and endurance. This isn't nothing to be worried about. It'll go away soon. You're past the crescendo. You're on a boat that just went through rough water. The boat is still rocking but the water is getting calmer and calmer as you get further away from the rapids.