Thanks for your query.
It seems to be musculo-skeletal in origin. Take pain-killers to get relief from it.
It can be broken ribs
. In such a case you need to go to the urgent care center or emergency room. Appropriate X-rays need to be taken. It will worsen if not taken care of. A history of injury
to the area is usually present.
It can also be enlarged spleen
. Spleen is an organ underling ribs in the left lower part of rib cage
An ECG should be taken to rule out heart pain.
Hope I addressed your concerns.