Wa'alaikumassalam! Aah, sakit bawah perut senggugut macam tu memang boleh jadi normal masa 36 weeks, don't worry lah. Usually it's just the ligaments stretching, baby dropping lower into your pelvis, or Braxton Hicks contractions (those practice contractions yang boleh terasa quite uncomfortable). Ramai mums experience this towards the end, so you're not alone!
That said, kalau sakit tu really intense, terus-menerus, atau ada bleeding or fluid leaking, better check with your doctor or midwife straightaway lah, just to be safe. Sometimes kram macam ni boleh jadi normal, tapi sometimes it's good to rule out anything else. Make sure you're drinking enough water and resting properly too, dehydration and tiredness boleh buat the discomfort worse.
Best to mention it to your doc at your next checkup so they can give you peace of mind! Semoga everything's okay, sis.