Answer:
First of all, what everyone says but it is true, drink LOTS of water. Even if you're needing to go to the toilet every 10 mins its worth it to rehydrate yourself. At only 2% dehydration you will feel thirsty. Make sure you're having snacks reguarlaly, bananas are good as they are high in potassium which slowly releases energy and keeps blood sugar levels at the right point. Eggs are good for blood sugar too. Sometimes you just need to stop, so try having a lie down, doing some deep breathing and relaxing, then getting up SLOWLY.
It could be an underlying cause though like iron defficency, if you're anemic or on your period your iron levels will drop dramatically. Take iron supplements and see if these help. Get the doc to check your blood pressure also.
Hope this helps.