I'm on the pill I stopped taking it last Saturday on the Monday I had unprotected sex & had blood spotting after it, I thought nothing of it & expected to come on my period. Wednesday I had the toilet wiped & had blood spotting again. Thursday I had a dark discharge after having the toilet and have had this blacky/browny colour since. I taken a home pregnancy test Wednesday and this said negative what could possibly be wrong ?

It could be. Did you take it in the morning? That is the best time to take it. Brown discharge is normal in early pregnancy so is spotting. You should probably go take a blood test at the doctors office. I hope I helped:)