2yo mild fever & next day rash on back. it went away then went on cheek and now seems to disappear then appear new spot dots on mouth too what is it?

Rash description is: too general, and if it moves from one location to another in less than a day, may be hives or heat rash. Lesions in the mouth are often found with a coxsackie virus referred to as "hand -foot-mouth" virus, but then there are lesions on hands and feet as well. If rash looks like a sunburn on chest, axilla and groin, it could be strep and child should be seen. Othewise, OK to observe a few days.