Hello,
From the symptoms the first possibility to be ruled out is of seborrheic dermatitis.
Seborrheic dermatitis is a common skin condition that
causes flaky,dry, white to yellowish scales to form on oily areas esp under the nose or anywhere on face. People with seborrheic dermatitis produce too much sebum (the natural skin oil). Later, pityrosporum yeast grows excessively in the sebum, sometime along with bacteria, making the dermatitis more persistent.