I am going through menopause and having night sweats and hot flashes. My hair has picked up the color out of my pillowcase and a red hat . I know this is hard to believe but,true . I have tried lemon juice, aspirin,baking soda mixed with shampoo and chelation shampoo and nothing works. I used a purple shampoo when every time I wash my hair to keep the color looking fantastic. I have had comments on my hair for the last 20 yrs. Can you help me?

Add a little bit of ash color in your dye.

One solution is to get rid of your red hat an whatever your pillow case color is, your night sweats may be acidic, the problem is I don't understand a 100% your question is it about you hair or your sweat?
If your hair is red, add a little bit of ash color in your dye.
For a couple of weeks before dying your hair , apply a little bit of warm olive oil on your roots massage gently and cover it , let the oil soak in at least 30mn before washing with a clarifying shampoo, condition well your hair after.Repeat this procedure a few times before dying your hair. It helps getting rid of the red dye from your hat.
If it is about your night sweat and I know it is horrible I have been there: it will go away the same way it came it take a while, but it will go away believe me .
One more thing , you can change your diet in order to calm the acidity in your sweat.
Good luck . Hope all this help...