Sayang, tu memang quite common dalam trimester ketiga, siapa nak kena tension, hormones berubah, dan dehydration. A few of my mum friends had the same thing around 36 weeks, and one swore it was because she wasn't drinking enough water and resting properly. Since you're so close to delivery, better check in with your doctor or midwife just to be safe lah, especially kalau berdenyut² macam tu, they can rule out anything that needs attention and set your mind at ease!