Chemical miscarriage ?

My periods are always regular so when I noticed I was six days late I thought I might be pregnant. For approx a week I had my normal menstrual symptoms and six days after my period was due I began to bleed - an extremely light, in amount and colour. Second day that would normally be heavier is still pretty light, darker in colour and with a lot of clots and am experiencing bad lower abdominal cramps (not normal symptoms for period). Is it likely i have had an early miscarriage, I have had these symptoms once before about a year ago.