Child Gets Rashes On Forearm, Thighs. Has Burning Sensation, Forms Scabs. Looks Like Petechia. Having Mild Stomach Discomfort, Tiredness. No Relief With Antihistamines. Suggestions?

What could this rare rash be? Begins on one forearm , burning sensation, then small red dots appear and within hours scab over. The following day another rash same size on other forearm appears, bright red and burning sensation and it travels to upper thigh one day another thigh the next and doc at urgent care says it is strange but looks like petechia. It s is a otherwise healthy child, feels mild stomach discomfort and tires easily. CBC is normal . Slightly elevated WBC but not alarming. We take her to dermatologist as now the rash is on face - began like a mild bruise under eye then cheek got red and the capillaries burst and it is scrabbling over and the dermatologist said she bet the child age ten is scratching it but she is NOT it is a burning sensation not itching. And it is uncomfortable and it travels the bloodstream what are your thoughts . Antihistamine do not work even though this dermatologist sau I d to keep child on it , mothers intuition sAys there is something going on