The last 4 months my periods have simply stopped. I'm a healthy 28.year old female and always had regular periods. I don't have any children. During the 4.months of no period I have had about 3 occasions of very dark brown discharge on tissue when I use the toilet but doea not last more than ten minutes. I have also been feeling extremely tired and achey, sleeping over 14 hours a day. I have done a pregnancy test and its negative. I'm not on any medication or been under any undue stress. Any advice would be grately appriciated.