What causes rash on neck and chest? itches

Many factors: Try to see what has changed - anew shirt, clothing that touches the neck area, new detergents, not rinsing off the laundry detergent properly, etc. If persists then seek help of a physician who can help control symptoms while a work up is started.

Many factors: Again you have to look at what you have started or changed recently. If the symptoms persist for more than a few weeks, seek the help of a physician who can help you control the symptoms while a work up is initiated.