Scaly, white flaky skin under beard.

From past few weeks I've been suffering from some kind of white patchy skin under my beard and mustache skin. The aggregated part on skin gets scaly & flaky just like dandruff. It was never itchy initially but now it occasionally feels and gets itchy after every late evening day. At very beginning, when I noticed, it was very little and with regular face wash and hygienic maintenance it was pretty much ok. But some times if I miss my face wash before bed in evening, then the part aggravated with itchiness. Now after having an look in the mirror, I found the affected part outline a bit red. Is this some kind of infection? Before this symptom happened to me, I used a shampoo which cause some allergic reaction over my scalp and I consulted a general physician and gave me flucort-N cream to apply on the affected scalp area. The condition got healed but now this had initiated ever since I started growing beard and using a beard oil.PLEASE ASSIST.