Lower Back Pain, Cramps, Delayed Period, Faint Positive Test. History Of Miscarriage. What Is Happening?

Hi I recently had a normal miscarriage last july. I had my period again on september 1-7. my period is late for 17 days now. I took 2 tests on the 9th/10th and it came out negative. I ve been experiencing lower back pains and last night i was cramping at the middle of the night. I took again a test on the 14th day it came out a faint positive. today, i peed and there was a light pink blood on the tissue but no blood on my knickers. What is happening?