For The Last Four Years. I Have Been Having Months

For the last four years. I have been having months were I do not have a period. Recently on the months i do hhave one the "old" never comes out. And I'vebeen dealing with stabbing pains in my right ovary, and lately iI feel like it affecting my walkin because my right knee feels stiff and my leg hurys all the time. Plus ooccasionally I have back pain. What is the issue I pray it is not serious