Red Itchy Rash, White Spots, Tingling Sensation, Inflammation On Neck, Chest, Arms. Cure?

i sudden got this saw pimple like red itchy rash ,you can also see tiny little white heads on the spots.there very tingling ,itchy and sometimes get very inflammed.ive been to the doctors and to the hospital and neither can tell me what it is,ive tried everything steroid creams,antibiotics,anti itch cream nothing is helping.i havent changed any of my powders/got any new products.i really need help is it so sore.its on my neck,chest and arms and all over my body feels itchy..