Episodic moderate pain in lower left abdomen under and below left ribcage. ultrasound negative. appetite healthy. sometimes seems like muscle. ideas?

Could be muscle: Often at the edges of the ribcage and illiac/hip bones where the muscle/tendon attach can be strained..Turning too quickly..Such as throwing a ball etc..Can cause a strain/pull on these edges resulting in inflammation and pain..At times lasting for months and much testing done without answer. A good physical exam is all that is needed for these cases..Check with your doc..Again..