It could either be your gallbladder or liver. Your gallbladder is just underneath your liver. If you find that you were eating fatty foods and then have the "sudden sharp pain under right breast", then it's probably gallstones and you need to see your doctor... Especially if it continues.They may do an ultrasound to see if you have any noticable gallstones or to see if your liver is swollen or enlarged.Hope this helps. :)