okay I need a little help here; I have been reading all these forums. Just confused...

Okay, I had a abortion done on July 17th. because Plan B failed. I had a normal period after that. Then I had my period this month on the 3rd and then stop on the 7th . On the 8th I had sex with my BF and the condom broke I took Plan B again on the 10th or the 11th can't remember which day but on the 11th I started spotting dark red blood in my underwear and have been having really bad cramps, and now i am spotting really dark brown red blood for 5 days now and having really bad back pain. I don't know whats going on and I really don't want to be pregnant again.. Not what I have been through last year almost loosing my son three times and once after he was born.. My son is going to be 9 mo on the 25th and its hard enough the way it is on me of raising my son and had gone through a c section alone on Christmas Day last year.. Just need some advice..