My skin gets very dry in the winter. Please share the treatment.

These days, perhaps because it's winter, my skin looks fine on the outside, but I'm really worried about the dryness inside. I moisturize morning and night, applying a generous amount of cream, and spraying mist frequently, but it feels moist for a moment, then quickly dries out again. Staying indoors with the heater on for a long time makes the dryness inside worse, causing my makeup to flake off. I drink plenty of water, but I can't figure out why my skin keeps getting so dry inside. How do you all manage dryness inside during the winter? If you know of any helpful treatments, please share them.