What Causes Early Menstruation With Large Blood Clots?

I got my period on the 25th day of my cycle, which is very abnormal for me. I regualrly get it on the 27-28th day. I have found discharges of large blood clots and tissue almost every time I urinate. I have no menstrual pains and almost never do but my stomach is very hard and bigger than usual. I feel like something is wrong. Should I see a doctor?