Hi welcome to Health care magic forum.
As you describe there is pain in the lower abdomen, some times radiating to the right side. since 3 months. It is present before and after the period.
The causes could be dysmenorrhoea, due to infection. there may be some gynacological problem, surgical hernia
, T.B.of iliocecal junction etc.
I advise you to consult a gynaecologist for diagnosis and treatment. You may need to have M.R.I. besides other routine tests for confirmation.
Wishing for a quick and complete recovery, and thanks for choosing H.C.M.F.