Eh, breast bengkak masa pregnant mmg common, lagi-lagi menjelang labor, hormon progesterone kerja overtime! Tapi kalau sebelah je yang bengkak, especially kalau ada redness, warmth atau sakit sangat, better check dengan doctor cepat-cepat in case ada mastitis or blocked duct awal-awal. A few of my mum friends had this around third trimester, and cold compress (wrapped in clean cloth) or gentle massage towards the nipple helped ease the discomfort while waiting for doctor's appointment, but definitely jangan self-diagnose, okay? How's the pain level, and ada discharge or any redness?