How To Treat An Itchy Bump That Is Spreading Along As Small Bumps?

I have an itchy rash on my back. It does not heal. New bumps start with a sting from the inside with a dot of blood. A raised itchy sore grows from this. It started with a few sores in 2006 and now covers my back with a few on my legs and arms. Nothing helps but benedril and calomine lotion. Some nights I think I will scream!@ It use to help the itching by taking the scab off but no longer. I am in poor health - diabetes, heart attach, stroke, seizures, blindness, tunable to walk, edema, night sweats, But the itchiness is the worse of it all.