Go up the road from the Sellia Backstreets Site of Grace until you find the church on the southern end. You can find Millicent on the floor in pain from a Scarlet Rot-inflicted illness. Millicent Questline is tied to Gowry in Gowry's Shack, right outside of Sellia, Town of Sorcery. There is no notable loot here outside of the Sacred Tear in front of the statue.