Welcome to HealthcareMagic.
can be due hormonal
changes , infection , menopause
.You probably have dryness due to hormonal fluctuation you had due to abortion
There are chances of infection too and this needs evaluation .I advise you to visit your Gynecologist and get examined and evaluated properly to rule out any infection.
Meanwhile you can use vaginal lubricants to avoid pain during sex and to reduce the chances of STD.