have a long tym allergy problem

um suffering frm skin allergy problem about 14 years.there occurs many pimples in my hand and leg specially which area remain uncover mainly in summer season.and those causes much itches.when those pimples becomes dry there become dark spot in those area.my hand and legs skin remain very dry all the year.doctors suggest me to use vaseline or oil to keep my skin moist .but it did nt improve my skin.um now in 18.plz save me