The first thing that comes to mind is a rash associated with a virus. My 9 month old had hand/foot/mouth disease and the first symptom was the fever followed 2 days later by a rash that was barely visible on the hands and feet, mostly prevalent everywhere else. In fact, he looked like he had the measles. Upon looking in his mouth, he had 2 very small ulcers on the back of his throat but these didn't show up until 4 days after the fever started. There is nothing to do for these poor little ones when they get this other than fluids and some tylenol. His lasted an entire week but some cases are less severe.