For the past few days i have felt like i was going to pass out or lose conciousness while sitting or standing. i eat and drink enough. why?

Could be from: low blood pressure, low pulse, anemia, or low oxygen. There are many causes, so you should see a doctor to help you sort them out. If you lose consciousness, this could cause injury to yourself or others around you.

Syncope: See attached link for further info. But if you don't actually pass out and merely feel light headed, you may have a lighter version called postural hypotension about which you can learn more at http://www.mayoclinic.org/diseases-conditions/orthostatic-hypotension/basics/causes/con-20031255

Need to get examined: Feeling of passing out is due to insufficient blood supply to the brain. If it occurs every time one sits or stands but not when lying down it suggests low blood pressure when upright. This can be due to low blood volume from dehydration or diarrhea or from acute bleeding. It can also be due to a disorder of the autonomic nervous system or adrenal insufficiency and from antihypertensive medication