“Late period or miscarriage?”

I am a 28 year old female. My last period was September 25th. I had unprotected sex on October 10th - no birth control either. I missed my period on October 25th, this was also a stressful time due to a big move (carrying really heavy stuff) and a career change. I was experiencing sore nipples, nausea and cravings (things I would normally never eat like jam). I took a hpt on November 1st (negative) and again on November 8th (inconclusive). Then I started spotting November 12th, with cramps every day since. Today, November 15th, I started having heavy bright red bleeding with large and dark clots - no cramping but severe back pain.

Is this a late period or spontaneous abortion?