Suggest Treatment For Itching And Pain On My Back Andchest

I have had a burning itchy pain similar to shingles on the left side of my back by the shoulder blade. I have no rash and it has been 8 days. the pain has now spread into my left breast area and is very uncomfortable. My Doctor prescribed gabapentin and I have been taking it for three days. Today I have started to have some relief from the burning pain but the pain in my left chest area has increased. Any suggestions????