Go to your doctors ASAP, this may be scabies ( a contagious skin disease caused by a parasitic mite, Sarcoptes scabiei, and characterized by intense itching..)
to stop the itching in the mean time, go to your local health store and buy a carton of EPSOM salt, (its cheap.) fill up a warm bath and pour about two to three cups of epsom salt in it. This will stop the itching
this could be a allergic reaction to something have you changed anything lately that you use try priiton syrup see if this helps follow the dosage for your age group if this dos'nt help my advice is see your gp because you also could have a viral infection.
A rash?? Chicken Pox?? Measels? What do the spots look like??