What Causes Brownish Vaginal Discharge And Back Ache After Embryo Transfer?

I did my ivf 3 days 8 cell embryo transfer on 25th january 2011. I did my blood test on 7th february and the result was 1.2 which means negative. I stoped my cyclogist pessaries imediately, i cried with loud voice for a long time and now i have light brownish discharge since than with severe back ache. Is there any chance that my beta hcg was wrong and i am pragnant?