My baby's eczema

We took Nathan to his 15 month checkup yesterday. He's doing great developmentally, was 23lb 3oz (fully dressed, so probably closer to 22lbs) and 30" tall. I asked about getting him allergy tested to see if there is something causing his eczema. It got a bit better after we took him off cow milk, but still is bad. So we have an appointment with a dermatologist next Friday. I don't want him to be allergic to anything, but it would be nice to know if there was something we could just avoid that would help his skin clear up. My younger sister is going to school for esthetics (skin care stuff) and has been great about asking her teacher for info on eczema. There's this hair loss shampoo or something, for people that get sores on their head from something, can't remember what exactly it's for, but she said that if you use it as a body wash it will help clear up eczema, it's called Nioxin or something. I still haven't gotten any because I keep forgetting. My SIL works at a salon where I think it's sold so I need to ask her if she can get some for me with her discount and I'll pay her back. At least Nathan's legs are looking better since we've made sure to keep long socks and pants on him at all times so he can't scratch it. He has 3 big spots on one arm that never seem to get much better though. Hopefully the dermatologist can help us out next week.