I have very sensitive skin and have found that DERMA products such as DERMAdoctor work well for me, and are available at Walgreens, CVS, etc. They have colloidal oatmeal and their products are good for dermatitis to get rid of the redness. Stay away from fragranced products on your face. If you're just looking for a gentle moisturizer, Clinique's daily moisturizer (pale yellow one) is so gentle and soothing. Also good is Clinique's moisture surge (pink gel). It's soothing as well.
Maybe you know what caused the flare-up....if not, it's most likely a product with fragrance or something else that is causing an allergy, or you are overdoing something that is harsh on your skin such as too frequent deep cleansing masks or brushes that are over-cleansing.
I know some ladies here are into double and triple cleansing at a time, but think how irritating that must be for your skin, especially if it's sensitive to begin with.