Itchiness is a sign of parasites. One of the best and least expensive formulas is Humaworm. In the meantime, get some cloves and make a tea with them. Also there are tinctures that contain Wormwood , clove, walnut hull, etc that you can also take. Steer clear of Sugar and white flour. Note parasites come out at night and more so during a full moon.
A coated tongue is a sign of candidiasis which is another parasite (they live off of the host)