I highly suggest that you talk to your primary care doctor
about this problem, since it has been going on for so long.
The way you are describing it, as areas of light skin tone that are slightly flaky and spreading over your body, definitely suggests tinea versicolor which is a fungal infection of the skin. Tinea versicolor often is brought out by sun exposure, but it can also behave as you are decscribing. Most of the time samples are not needed to diagnose tinea versicolor, as it is very common and your doctor will know what is going on. Usually, it can be treated very successfully with topical over the counter antifungal creams, although sometimes your doctor will prescribe something stronger.
There are a few other conditions that could be going on and that your doctor will be able to rule out. The other most likely is eczema
, which is an inflammation of the skin caused by too much dryness, leading to redness, itching, and scaling. Eczema is not treated with antifungal medications, which is why it is important to tell the difference. Rather, it is treated with steroid creams and with good skin care and moisturizing ointments.
Talk to your primary care doctor for further advice.