Uy, totally normal yan sa 36 weeks, lalo na kung first time mo, ang baby ay bumababa na talaga para maghanda sa labor kaya that heaviness at pressure sa puson is expected, at yung Braxton Hicks contractions (yan yung tigas ng tiyan mo) ay super common na this late in pregnancy! A few of my mum friends had the same, one swears na ang best help ay matinding stretching, prenatal massage, at pag-upo ng tama para sa back pain, but honestly, since may pain ka sa likod at balakang, mas better na i-confirm mo with your OB kung normal lang yun or if baby's position needs checking. Kaya mo yan, mama, malapit na!