Salam! Sayang, discharge berwarna kuning with bau and gatal especially when pregnant, please don't wait, go see your doctor or KK as soon as possible, okay? Even if tak emergency level, better check now sebab you're at 30 weeks, and these symptoms need proper check-up, bukan main-main. A few of my mum friends had similar thing and the doctor sorted it out quickly once they went in. Take care of yourself!