Uy, yan ay common sa pregnancy, lalo na sa 5 months when your ligaments are stretching to accommodate baby, a few of us moms experienced that exact sensation, parang hihilahin ang tiyan tapos maglalabas lang. Since it started kahapon lang at hindi consistent, it's most likely ligament pain, pero honestly para ma-ease your mind, better check with your OB just to be sure everything's okay, especially pag may cramping or bleeding pa. In the meantime, try to rest more, avoid sudden movements, at mag-stay hydrated ka!