My child was complainin of a sore tummy an now he has came out in a rash all over his body an behind his ears. he has had the chicken pox before,

Likely enterovirus: Many intestinal viruses will enter on contaminated fingers & travel to the intestines where they can cause fever, cramping & or diarrhea. As the body responds & fights off the germ it often comes to the skin surface as a pinpoint rash. Some may also have a blister quality but that is less common than the pinpoint red dotty rash. The rash will generally peak after a few days & disappear gradually.