Hi, welcome to the health care magic and thanks for asking your query here there are variety of medical conditions which may cause pain in left upper abdominal area including some lungs, spleen and colon disorders if you have no other symptoms like fever ,cough etc and u r otherwise healthy person then this pain might just be related to pulled diaphragm muscles and is not a serious concern For this you should rest properly and take over the counter pain medications like ibuprofen to relieve pain But if your pain do not subside within 3-7 days and it accompanied with other symptoms such as coungh and fever than i would strongly suggest you to visit your GP to get it examined to rule out other underlying medical conditions including a pleurisy of lung or spleen disorders I hope it helps Thank and get well soon