What Causes Delayed Period, Lower Back Pain And Tearing Sensation In C-section Scar?

I am 40 years old with 2 kids. I m experiencing lower back pain, and a painful tearing sensation in my c-section scar(had a c-section 8 years ago). I also just started feeling nausea and light headed. My period is late by over 2 weeks. I have taken 4 different home pregnancy tests, they were all negative.