Whenever i over-eat sugary &/ wheat foods, i come down with a cold within hours or the next day. why?!

Immune suppression: This is a bit unusual but sugar is well known to suppress immune function thus lowering your resistance to infection- see http://www.Immunesystemetc.Com/sugar.Html wheat raises blood sugar so that could explain why you get colds after wheat, but you might also be allergic to wheat or gluten. In either event it would be wise to avoid these foods.