I agree..this could be something serious that could be sorted out with a trip to your doctor..( I don't mean that to scare you) it could be anything. But once you've got the right medication this should go away... Tell someone to take you as soon as you can.
There are too many things that can be wrong for me to say, you need to see a doctor as soon as you can!
There could be a numbers of reasons,high, or low blood pressure,high or low blood sugar count,dehydration but you will never know without proper diagnosis,you can have your blood pressure checked at your pharmacy but can not get medication without seeing a doctor.