Folliculitis Decalvans is a terribly aggressive disease. I have seen this appear in a couple of patients over the past 27 years in practice and it is difficult to manage. I would consider an alternative like Scalp MicroPigmentation which will not be aggravated by this disease.
See here: https://scalpmicropigmentation.com/bold-shaved-look/
You seem to keep your hair cut short and that means you would be an excellent candidate for this procedure as it will cover all of the scarring on your scalp.