Pain in upper left abdomen near rib cage. xray of ribs and blood work on spleen normal. what else could it be? ulcer maybe?

Many things: Costochondritis of anterior rib not usually seen on xray. Pain in upper abdomen can because by different organs in region.Pancreatitis, gastritis or ulcer, duodenum with duodenitis or ulcer,colitis , and eophagitis and reflux can cause upper abdominal pain. Endoscopy of the esophagus, stomach, and duodenum often reveals the problem .Should be referred to gasroenterologist if symptoms continue.