My kid keeps scratching herself

Find the root cause of why they're scratching themselves. If they're too young to speak, look out for dry skin or redness - that could be a sign of skin conditions like eczema or dehydrated skin = you should look into moisturizing products like coconut oil, aloe vera etc. If there's no physical signs but constant scratching, you might want to try and identify when this started to happen, when it happens, how long does it happens and what makes it stop. It could be something they saw and copied, something they do to get your attention, or something that is bothering them under the skin which needs medical attention :)