Hi, Thanks for writing in. I guess you have got ultrasound scan done for your kidneys and that shows a slight difference in the sizes. In normal individuals, the sizes of kidneys when compared, can differ by about 2.0 cm and this is acceptable. Since your kidneys are within the acceptable range of difference in size therefore it is not a concern. The kidney stones need to be treated after consulting the urologist. Two stones each measuring 0.4 cm in the right kidney are not a serious problems unless there is obstruction. As you are having pain also, it is important to consult your doctor and take anti spasmodic medications to relieve the pain. Drinking lots of water and visiting washrooms frequently is recommended to flush the stones out of your system. If the stones have entered the ureters and are on their way to the urinary bladder then you might experience a sharp and severe pain lasting for hours to days. This must be confirmed first and usually treated by giving medications of alpha blockers group which cause the stone to move forwards and reduce the pain.