Milk/heat/saliva rash

My baby has redness under those neck folds too. It’s so hard to clean. I try cleaning it with cotton balls with water before bathing, gentle cleaning it again with my finger during bathing time. Pat dry with towel and apply a thin layer of hikada horse oil (can be found on Lazada). When baby is not sleeping, I make her wear a bib to stay dry. The condition improved after a few days.