Most women do not experience any sort of discomfort after the HSG procedure. However there are some women who have reported minor crampings which eventually passes away after 5 minutes.
During the procedure the cannula provides a smearing sensation. And when the dye is injected you might feel warmth inside of you.
If you have a blocked tube and the dye is injected then a surging pain might be felt. This is caused by the dye pressing against the blockage.
After the procedure cramping might be felt. Women who feel pain during the pelvic examination are more prone to cramping though there is no scientific proof to back up.
Before an hour of HSG procedure, painkiller is prescribed to cope with this common pain. However, in rare cases the cramping might prevail for hours which also can soothed through medications.
Iodine allergy (the dye is iodine based) can trigger an allergen reaction. If you are allergic to shell fish then you are also allergic to iodine (generally). Talk to your doctor about it before the procedure.
If fever shoots after a day or two after the procedure contact your doctor as it might be a sign of infection from the procedure.