Mama, abdominal pain at 38 weeks is quite common, a few of my mum friends had the same thing dekat final weeks, terutama bila bersin or laugh because of the pressure kat perut yang dah penuh dengan baby. Tapi since you're already scheduled to admit on 18/02, I'd say mention this to your doctor during admission atau call the hospital now to confirm it's normal, sebab they'd want to make sure everything is okay sebelum labour. Sakit pinggang yang hilang might mean baby's position is shifting too, which is actually a good sign, tapi let the medical team check just to be safe, okay?