Upper abdominal pain during periods

I have been diagnosed with endometriosis and relate to lower abdominal pain, but for the last six or seven months I have been suffering from upper abdominal pain. It is between my rib cage and my navel. I suffer from this pain during my period and on the first day, get terrible bloating and vomiting and I am constantly woken up at night with a sharp, gnawing pain in the upper abdominal area.  The pain is a lot worse than my lower abdominal cramps associated with periods, which I take Mefanamic Acid (ponstan) to alleviate pain but they do not relieve the upper abdominal pain. I also have a lack of appetite and am in more pain after a meal.