D&c 10 weeks ago for blighted ovum at 12 weeks pg, bled for 4 days after then stopped but bleeding every time after orgasm now, why is this happening?

Still healing?: Orgasm induces vigorous contraction of Fallopian tubes, uterus, cervix, and vagina, which may lead to spotting blood from incompletely healing of mucosa from D&C. So, it's still logical to be patient and see as long as the spotting is slowly but surely becoming lighter and lighter. If spotting still lingers beyond 4-5 months after D&C, see your Gyn-doc for reassessment and counseling. Best wish...