Loss of appetite

So, the past 3-4 days, i have barely had any appetite. I literally eat a granola bar for breakfast and a few crackers or some ice cream in the evening (it is all that doesn't make me feel nauseous at the thought of eating it). I have lost 8 lbs (im overweight so it comes off faster) but im also having some pain like 4 inches above the belly button and head aches that are excruciating when i move my head quickly. Im traveling tomorrow morning and am wondering if anyone has any suggestions of what this could be?