How Can I Make Homemade Soap And Shampoo?

I’ve developed some kind of allergic reaction to store bought soap and shampoo and was wondering if I could make my own insead.My skin has become very irritated and my scalp burns every time I shampoo and then it gets scabs shortly after shampooing.My face after washing becomes bright red and burns,it’s awful.I even tried soap and shampoo from a place that claims to use all natural ingredients but it didn’t help.Any suggestions on how to make my own?