Uy mama, sa 36 weeks yan sobrang normal na, lahat ng kaibigan ko nag-complain ng ganyan sa third trimester, the weight and pressure down there talaga ang culprit! But since may stomach pain ka na rin, I'd really suggest checking with your OB just to be safe, kasi sometimes it's just Braxton Hicks or the baby's position, pero better peace of mind, diba? In the meantime, try pelvic support shorts or maternity belt (sobrang tumutulong talaga), avoid long walks, at sleep on your left side with pillow between knees para sa back pain, hopefully makakuha ka ng better rest soon, mama!