hi there, spotting after positive pregnancy test could be due to
bleed which is mostly only spotting and last only for few days
or missed abortion
inwhich case there will be a longer bout of bleeding and a negative pregnancy test after a few weeks
3.ectopic pregnency with nonviable embryo and withdrawal bleeding following that.
You can do a repeat pregnancy test and an abdominal ultrasound
which will be able to guide you to the viablity of the fetus and the position of the gestational sac
. Depending on these your obstetritian will be able to guide you to the further course of treatment and management. Hope this helps. Take care.