Girls, I wrote four days ago that my cycle is 35 days and I got confus…

Girls, I wrote four days ago that my cycle is 35 days and I got confused on day 29, as it seemed like period started but there was a clot with some heavy bleeding on the third day after starting. I felt a strong pull in my lower abdomen on the third day and a small clot came out with some blood. Has anyone experienced this? What could it be? Because for the first two days everything was normal, no pain or clots. The next day everything was clean ?‍♀️. No periods have come like this before. I can't do a test.