Aiyoh, at 12 weeks memang normal lah sakit kejang-kejang macam tu sebab baby growing, tapi kalau terasa macam ditarik-tarik sangat or ada spotting, better check dengan doctor je untuk peace of mind, a few of my mum friends also had this during first trimester, some turned out tu just ligament stretching, some just perlu rest more. Try lie down, relax sikit, and make sure drinking enough water, sebab sometimes dehydration pulak yang bikin cramps terasa lebih teruk. Kalau yang persistent or getting worse, jangan tangguh, call your clinic, better safe than sorry masa pregnancy!