I am a 15 year old girl and in the beginning my period was fine but when I was 13 my GP prescribed me mefenamic acid tablets 500g because of my heavy period which lasted 3 months but eventually stopped without the use of the tablets. The last time I had my period was in march 2014 and now its nearly august 2014 and I haven t go my period. I m not sexually active and I m really worried and I get lower abdominal pain and cramps but no period