Hello, i am feeling this crazy tingling under my left shoulder blade. it feels so odd but doesn't hurt. could it be serious?

Perhaps not so: Some patients will rarely experience a tingling irritating sensation over the middle of the shoulder blade or even below, and that is a problem locally perhaps secondary to trauma or virus, termed notalgia paresthetica. A thoracic disc may compress an intercostal nerve, and cause symptoms. Probably not a sign of progressive disease, but have your doctor examine it.