I used to have kidney stones in my kidney. but now i think they passes. but my kidney hurts so bad sometimes and dull pain is always there.

You need examination: You may have passed some "stones", but that doesn't mean that your problems are gone. More stones can form and if one is blocking the ureter (the tube that drains the kidney), you may have pressure pain from that blockage. Blockage can also cause infection that is painful in the flank/kidney area, especially to jarring. You need to see your doctor and get studies done on your kidney, soon!

May be some stones: There may be some stones still present. If pain persists, becomes more severe, or if you are unable to urinate, seek immediate medical attention