rashes and tiny bumps

I have these rashes all over my bidy, but mainly my stomach, back, shoulders, neck and upper arms. They consist of tiny bumps that really itch. At first I thought It might be the Chicken Pox, but I had them when I was a child. Also, when my sister looked at them she told me the bumps were toosmall to be chiken pox. At first it was just one or two bumps here and there but the past two days has brought many many more. I just want to know what this is. I am very tired, no appetite, nauseous, cold, irritable, itchy and scared. Please help. All advice welcome.