So i had protected sex for 5 minutes once this month ( between my cycle) , and my period was suppose to come jan 13. 

so its already the 23rd i still dont have my period, and i took 3 pregnancy tests and all came out to be negative.

today ive been having lower back pain, and thiught i would be on my period

instead i saw brown, like old blood discharge, and then this mucus, gooey,a nd slimy discharge from my vagina, does it mean im pregnant?!? 

is it normal?? what does it mean??