is this serious?

I (26f), have been dealing with the flu for the past few days. im not sure if this is relevant to the issue or not, but I thought I would include that. I also want to mention that I have always had irregular periods. yesterday evening, I suddenly started bleeding very heavily. I am going through pads about every hour or so. I am bleeding through my clothes, etc. I am also passing large clots, about palm size. I havent felt light headed, just a bit weak. not sure if thats from the bleeding or the flu tho. is this an emergency? when should I seek help?