What is going on???

Ok so I'm 4 days late. My calendar says I'm on cycle day 36, and it's usually between 29-32. I've been cramping a lil. Last week I went to the bathroom and there was like a gooey string of blood and that's it, I've cramped a lil..not too much though. I've taken 2 tests and both negative. I'm guessing I should just make an appointment with my ob and find out what's going because I'm usually on time. 😩