Could Dark Brown Painful Spotting After D&C Be Due To Tight Cervix?

Dr, M 34,got my d&c done ( july 2010) after blighted ovum.i was prescribed along with other medicines premarin for 3 mnths. during that period i had my menses regularlary, bt every mnth i had spotting which went on for 3 to 4 days and smtimes it turned into bleeding. Since 2 mnths M having d same prob of dark brown spotting which is now very painful, i was out of station so had a telephonic convers wid my gynae, who says its all because of tight cervix, still m worried.