What Causes Red Rash On The Lower Neck And Front Of Shoulders?

I have a red flat rash on my lower neck, front of my shoulders back of both wrists
small area on my forehead and on the middle of my back, Then I also have red dots on the top of my thighs. All of these are itchy and hot, I also have had an annoying cough with this rash nothing barking or wheezing. Also my scalp has been itching intensely along with the palms of my hands.