I used to have severe eczema and dematitis that produced horrible itchy and giant flakes in the scalp. It was just nasty and super embarrassing. I used Nizoral shampoo to wash (which can be a bit drying to hair) but it releived the scalp flakes and helped with the itching. After shampooing, I had to put conditioner ONLY on my hair - not on the scalp. This was really important. So the process -
make sure hair is completely detangled and apply shampoo to the scalp using a bottle with an applicator tip. Gently massage scalp, let set a few minutes and rinse. Be careful to not tangle the hair.
Next, I applied tea tree and lavender essential oils straight on the scalp and the emu oil which helps the eo's penetrte more deeply. Again, small bottles with applicator tips help make this process fast and easy.
Next, apply conditioner to hair only.
Wait about 10ish minutes.
Rinse everything really well.
Finally, apply a mix of the essential oils with emu only to the scalp. Make sure whatever products go on the hair do not go on the scalp until the condition improves. Chemicals in (IMO) many shampoos and conditioners will make dematitis worse.
She probably does need to see a doctor to rule out a more serious problem, because these treatments (mine and others) are only topical and will not focus on any underlying issues.
She needs to drink lots and lots of water. Avoid sugar if possible, avoid fried foods, avoid as much white flour as possible. Eat yougart with active yeast cultures (check the label) and lots of fruits and veggies. And did I mention the water? Has she considered doing a cleanse? The Master Cleanse is almost easy after the first three days. Flaxseed and fish oils to increase her intake of EFAs would also be beneficial.
I feel for her - when I had this problem, it was so horrible. I would scratch until I made my scalp bleed. Ewww.
Ultimately, a diet change and a few changes and products in how she cares for her hair will help.