PMS or Pregnant?

Hey ladies! Are these normal PMS symptoms for anyone?? I've got super sore nipples a week before AF; cramps, Low back pain. Also been getting nauseous after 5pm the last three nights and super tired. Smells are crazy too! Two days ago I had a single spot of blood when I wiped. Is that normal to spot before AF, or could it be implantation? CD 21, 7 dpo! AF DUE IN 7-8 DAYS. 
Had been on depo since I was 16, (now 24) and just recently off I've only had a few periods since, so it's like this is all new to me again!!! Thanks for any input! 🙂