HSG injection is given generally to increase the chances of pregnancy. It will help in progesterone
formation from corpus luteum
One of the side effects of the HSG injection is abdominal pain
. So, your occasional cramps may be because of the injection.
You can take some form of analgesics to decrease the pain.
If still not subsiding you have to visit your doctor.
If you want to know whether you are pregnant are not now at this period of menstruation
better go for blood test
to detect pregnancy.
It is not like urine test which can be done at home, blood test should also done by the doctor. So, visit your doctor.