Breastfeeding pain!! Help!!

Sandy
As of the last two days it is extremely painful when one of my twins latch on to my left breast. I have no redness or bumps, but it hurts so bad that I immediately take them off! When they latch to my right breast we have no pain or problems at all! Could it be a clogged duct? This is my first time breastfeeding and I have no idea what is happening. Please help!