How Can I Get My Periods?

Good day! I am 51 days delayed to date The history of my menstruation was never on time. Although I will be delayed for days but never for 40+ days. I had a pregnancy test on the 48th but it came out negative. I have been experiencing severe abdominal cramps and shortness of breath, occasional back pain and vaginal pain. I tried a lot of ways (proven in my case) to induce my menstruation but until now, I have no signs. What is this? Thank you.