Has this happened to anyone else?

So my periods are usually 40 days apart. My last period ended 25 days ago. And yesterday I went to the restroom and there was a lot of blood. I thought I started my period early. So I put in a tampon and went about my day. When it came time to change there was barely any blood on the tampon and I haven't bled anymore since. And there was ALOT of blood...anyone know what this could be?