What Causes Stringy Mucus In Menstrual Flow And Stomach Cramps?

hi, normally my periods are always on time and heavy and painful. this time it is lighter than normal and it was four days late. ive had slight cramping and it started out brown then went to bright red for a few hours and now its pinkish brown with bits of red and has stringy mucus in it. is there any way i could be pregnant?