Eczema Treatment Care

I know it’s contact dermatitis because I’ve looked it up on the internet. I’ve never had eczema before and it’s only on the back of my neck so I’m pretty sure it’s coming from this new stuff I’ve started using in my hair. I’ve stopped using stuff in my hair but I want to get rid of the eczema. I’ve been broken out since Tuesday. At first it was really itchy and I just thought it was a bug bite on my neck but then it started spreading and now it’s all scaly and sore. What are some creams I can use to get rid of it? Also can I put halloween make up on top of it?