Rash on arms, face and stomach?

I have a rash that started on my lower rt. arm appoximatly 3 wks ago. then a week later I noticed bumps on my upper arm. A few days later on my face and neck. And now my stomach is covered as well. Today more spots on my left arm. Nothing on my legs at all. It itches terribly and is somewhat painful. I can't find any photos on line similar. Any ideas. I have not been using new products, eating any diff. foods and have only been around the house or grocery store.