Wa'alaikumassalam sis! Honestly, sakit ari-ari especially yang repetitive macam tu, better check with your doctor or midwife cepat je, especially since it's happening regularly. At 27 weeks, dorang kena tahu pasal ni to make sure baby and you are okay. A few of us dalam group pregnancies had similar niggles, tapi ada yang normal stretching pain, ada yang kena monitor lebih, so really bergantung on your situation. Jangan tahan sendiri, go get it checked out ya!