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.