What Causes Alternating Heavy And Light Bleeding, Clotting, Cramping With Irregular Periods?

for the last four weeks my period has been strange two weeks i bleed heavy then for a week i spotted light pink and now im extremely heavy again and passin large clots approx 6 in the last 12 hours mainly golf ball size but one about baseball size. im not fillin up pads like crazy but i start feeling pressure and i go to bathroom barely sit down and it gushes out. since my tubes were tied ive been very irregular sometimes going 3 months without. i'm cramping pretty bad and was wondering if i should be worried or be seen by a dr asap