Scalp and neck are actually very classic eczema spots for toddlers, so it could be worth getting a proper diagnosis first rather than just trying different products. A paediatrician or dermatologist can prescribe a mild topical steroid for the red, itchy patches, that's usually what actually clears the flare, since moisturiser alone often isn't enough once it's already inflamed. Do loop in your doctor before trying anything new, especially on a toddler's scalp.