Why has my skin become dry?

I've never suffered from dry skin before, but for the past couple of weeks my skin has been flakey and peeling constantly. it's mostly noticeable on my arms, legs and face. None of the conventional explanations make sense: I haven't been out in the sun, I'm drinking plenty (more than usual to try to counteract the dryness); my diet hasn't changed and is as nutritious as ever; I haven't been using any new skin care, make up or hygiene products. It's not itchy so it can't be eczema or contact dermatitis. Using lotion and moisturisers hasn't helped. Does anyone know what might be causing my skin dryness or have any tips to try to cure it.