I have an area below my shoulder blade on my left side that feels numb but is very itchy at times. there is no pain just a very odd sensation. ?

Medial branch: This could be a problem with the "medial branch" nerve that comes off the main nerve root as it exits the spine and innervates the spinal joint and overlying skin just to one side of your vertebral column. The opening could be narrow for the nerve, or this could be subclinical zoster without rash (shingles) activity that will settle down (shingles most commonly flares on the chest wall).