Spotting after sex, every time,no blood without sex, had d&c abortion 35 days ago and no period till now,hpt negative, what is the reason of spotting?

You Need Testing: If you are spotting after intercourse 35 days after an abortion, you need to see your Ob/Gyn. There are some rare complications that can occur after the procedure such as Gestational Trophoblastic Disease. Though rare, its serious enough to warrant a trip to your Ob/Gyn for a blood test and possibly other testing. Best wishes!

Many possibilities: This makes me concerned for an infection in your cervix, e.g. an STD. Other possibilities include cervical mass, cancer, and normal.