I suggest first you try a week course of anti-inflammatory drugs like brufen. If the pain doesnt settle you can have the following possibilities. Also take a month course of multivitamins.
As per what you have mentioned , you had D&C approx. 8weeks back. Sometimes after D&C , the next period gets delayed as most of the endometrium gets removed during D&C which is shed during a period.
Sometimes due to incomplete D&C some products of conception are left behind , which can cause pain lower abdomen, cramps and off and on spotting with no menses.Rare possibility is asherman's syndrome which is scarring/fibrosis
of the uterus due to excessive curettage during D&C, folllowing which no periods occur. It can also cause chronic pain
. You should get a repeat ultrasound
as it would rule out both scarring and if any products of conception are still there.
Lower abdomen pain can also occur after D&C if some inflammation has occured which can also lead to backache
If you also have complaints of itching and vaginal discharge
then it might be due to genital infection
For periods you can use progesterone
tabs for withdrawal bleeding which will also help you to exclude ashermanns syndrome as if menses occur following progesterone use, its not ashermans.