Mild dandruff after 5years

Hey people, new hear but in need of advice (and happy to help others)
hair type : black curly medium length
Ive been water only for roughly 5-6 years, only ever using coconut oil (not even sure why) every now and then before a sauna (sauna heat would even the oil out) but the last few weeks ive had itchy dandruff and as expected its annoying!
ive had a trouble free time water only and ive got great curly locks!
Been contemplating a natural shampoo, but will that just remove the dandruff and it will start from zero? not to sure how to treat it!

thanks in advance