The pain that you are describing underneath the rib cage is probably due to the injury caused during sport activities and may have resulted in a sprain. However it can also be due to fracture of the ribs. Symptom of rib injury depends on the type and severity of the injury. There will be pain at the site of injury and also increases on deep breathing, cough, sneeze and even laughing .Rib injuries may occur due to motor vehicle accidents, crush injuries, after a fall from a reasonable height or assault. I would suggest you to get a few investigations like Chest x ray and C spine x ray. We can rule out any fractures. I would advise you to wear chest brace, physiotherapy and use painkillers like ibuprofen twice a day for a week. This usually subsides in a month or so. If it worsens and daily activities cannot be performed then you could consult your doctor.