Hi…I took my 10 year old son to the ER do to severe pain under his lower rib cage. He was not able to take deep breaths or stand completely upright. After several hours in the ER the pain subsided and we were sent home. An ultra sound was preformed during our ER stay and revealed nothing worth notating with the exception of “Free Standing Fluid” found in the abdominal cavity. Is this something that I should investigate further? What type of doctor would I consult with about the Free Standing Fluid?