Sharp Pain In Rib Cage Area. X-ray Done. What Could Be The Reason?

My dad just told me that he got a sharp pain in his rib cage area while working on a driving lawnmower...he assumed it would go away. After a few days, the pain has been persistent in the rib cage area. He went to Kaiser where they did an X-ray . He said he kept seeing this red dot appear while the tech was conducting the X-ray. The dr. Asked him if he could have an shrap metal in him...he is a Vietnam vet, and did have this in his leg when he stepped on a mine. The dr told him, I have no idea what the hell this is. he said it appeared as a white dot on the X-ray. He is awaiting his results, but I am very worried.