Our daughter is 6 y.o. For the last three weeks or so, she has been experiencing constant and increasing itchiness all over, with no apparent rash . She describes her itchiness as a biting, crawling sensation underneath her skin. She is also complaining of muscle achiness and a vague feeling of illness (headache, upset stomache). Antihistamines help to make the itchiness more tolerable, but there is still significant itchiness. We see no signs of body lice or scabies (e.g., burrowing). Please help.