What Are The Red Itchy Rashes I Am Having All Over Body?

For over a month now I have been experiencing red itchy rashes all over my body. It looks like loads of mosquito bites, varying in size. It then leaves but will randomly come back in perhaps the same or different parts of my body. When on my hands, they turn into what looks like tiny blisters, with water underneath? There are no other symptoms. I have had no dietary changes and I changed washing powder but nothing seems to work.