Do you have nausea, bloating, distension? Do you have history of stone passing or family history of stones or heart disease? Are you diabetic? Are you on any medications? Is there any tenderness (pain on the area when you press)?
Do you smoke? Take alcohol?
Following would be considered for the cause of this pain;
1) Renal colic (kidney stone): they are one of the severest of pain
3) Related to lung, pleura (covering around lung) or heart or blood vessel
I have enumerated them in the sequence of incidence with your clinical presentation. As a matter of fact, any pain which is classified as severe (above 6 or 7 on the scale of 0-10), should be evaluated by a physician and investigations and imaging studies done to ascertain the exact cause. So it would be prudent to consult your physician for a clinical examination and get further investigations like chest x-ray, ultrasonography and blood work up, if needed.
Please feel free for your follow up questions.