Upper abdoman pain, light headed, nausea... was vomiting at first but no longer... what could this be?

Gall bladder, ulcer?: Depends on location, duration. Could be gallbladder attack (right upper quadrant/midline pain, often goes to back), pancreatitis (midline, often going to back), inflammation of stomach/duodenum/ulcer (midline, left upper quadrant), less likely kidney, colon, referred pain from gyn, or appendix. Call your doc. Fever, jaundice (yellow eyes/skin, dark urine, light stool, ongoing? -er.