Hello. I had my first few menses normally with no pain. But after that i started having unbearable pain on the first day of periods i have to take painkillers everytime. I went to a very renowned gynaecologist and on cheakup i found that i hav hypothyroidism. My periods occur normally from starting with the cycle of 25-28 days. My mother also had this kind of pain and her mother too both my mausis have thia problem too.