What Causes Irregular Periods & Clotting?

Im 28 and had 2 children i do have pcos and have irregular periods i never have period pain or clotting however i started 12 days ago with a brown discharge that then turned to bleeding which has now turned to clotting with one yesterday being as big as a golf ball and was uncomfortable coming out i also am very tired now and continuous tummy aches and my entire back aches today and ovaries... :( im going through about 1 and a half packets of 12 sanitry pads a day... can someone please advise