Random itchy bumps on skin?

I am 16 years old, and lately I have had a severe itch. Randomly I will get a rash that breaks out as a cluster of little tiny bumps and itch. It gets worse at night, and I also get it on the outside of my wrist the same time everyday. It's mostly on my back, chest, ares, and butt, but it occurs random places as well. my chest and upper arms itch extremely bad when i get out of the shower. I have changed my soap to the homemade soap my mom uses. It started to get worse after I got a sunburn all over my body. Please help me, I can't sleep at night it's so bad