This is classic toxemia,
A build up of toxins in the system caused by overeating, poor diet such as sugary foods as laurel mentioned, overly processed foods, drugs and medications and other chemicals which assault our systems. I agree with laurel that sugar is particularly bad news.
These chemicals overload the organs of elimination such as kidney and liver and force the body to use secondary forms of elimination such as rashes, fever hemorrhoids etc.
A lengthy fast on water only is recommended followed by a complete correction of the diet and living habits. Sufficient sleep, exercise and sunshine upon the skin are essential elements of Natural Hygiene.
Research Natural Hygiene
http://en.wikipedia.org/wiki/Natural_Hygienefor more information or by typing "Natural Hygiene" in quotes.