welcome to healthcaremagic
from the description it seems it will be better to consult physician/dermatologist
clinical examination and some tests are to be done to have a diagnosis for proper treatment complete hemograms with platelet count
and b.t. ,c.t. to be done to exclude hematological disorder
rashes with itching may be urticrial rashes
the rashes in thigh are not due to friction of the thighs ?