From the description you have provided it could be seborrheic dermatitis
To treat the same,
Use a mild cleanser and moisturiser to combat dryness like cetaphil cleanser and moisturiser
Use a steroid and antifungal lotion or cream over red scaly lesions present over chest, face, abdomen etc like mometasone terbinafine
If lesions are too itchy, take oral antihistaminic( cetirizine
If scalp also involved use sebowash shampoo every alternate days and also apply steroid antifungal lotion.
Application of plain antifungal cream or lotion would give suboptimal results.
Hope that answers your query. Take care.