Do Estradiol Injections Cause Sporadic Spotting?

hi my name Maria and am 42yrs.old,wt.156lbs,5'2 and had a bileteral oophorocystectomy back in 1999 and i have had spotting of my menstrual period here and there,but recently started therapy of estradiol injections and since then have had spotting episodes some heavy and some lite,is this normal or should I stop the estradiol.you see I have no medical insurance at this time cannot really afford to go see a doctor.what should I do?