What Causes Body Rashes And Itching?

i have been having a body rash from the past few days. i see it mostly when i wake up in the morning. its basically like tiny bumps on the body, i.e, on the hands, back, and a little bit on the thighs and buttocks. its not much on the hands now, but there are a few bumps on the back and thighs and buttocks. they are not very red or itchy,but tend to itch if i scratch the area. Also i started getting these rashes with the start of the rainy season.