Pain in the upper left abdomen and chest area can be due to
stomach issues (GERD or hiatal hernia), spleen issues, due to an
abscess below
the left diaphragm, a hematoma (localized collection of blood), an abscess, or a muscle pull (as it happened while playing). Ultrasound would have ruled out spleen problems and an abscess below the left diaphragm. A CT scan would be more diagnostic.
Do discuss this with your doctor and get yourself examined. Take care!