Think I've found the answer (atleast for myself)

32 male who has been suffering from scalp and back acne (folliculitis) from the age of 18. It's carbs guys, I'm begging you, just cut out carbs for a month and tell me here if it works for you. I've taken hundreds of medications, tried every shampoo under the sun. Tried almost everything suggested here.

I've always noticed that my scalp folliculitis reduced when I went on a diet and ate clean. In these diets I just ate less and worked out more but invariably it reduced my card intake. I'm on a high protein high fibre diet with very less carbs for a month now and my daily intake of carbs is surely always less than 50 grams because I measure my food every meal. I used to drink coffee with sugar and blamed coffee for my flair ups but it was the sugar. I've basically eliminated anything that has simple carbs like sugar, refined wheat, rice and things like that. I still eat vegetables and little fruit because I'm not bothered about complex carbs. My hair is way less greasy and don't need to wash it every single morning like I had to.

Please try it for a month, I think it'll help a lot of you.