Skin rash?

I have a rash on my right arm. ITs been there for about 2.5 weeks. It consists of little red bumps and clusters from my elbow to my hand junction. It itches intensley. Sometimes it seems to be going away then comes back. Does anyone know what it is, or how it can be treated?|||It could be atopic eczema. Try a little over the counter hydrortisone cream to see.