When i reach, what is that stabbing pain between my shoulder blades?

See Orthopedist: Commonly, shoulder blade pain can be from the neck or bursitis around the blade. The abdomen, heart and neck can also refer pain to the shoulder region. Ribcage pain from rib joints can cause pain around the shoulder blades. Shoulder problems such as arthritis, labral tears, instability, tendinitis, rotator cuff tears, bursitis, painful bony spurs etc may need to be considered as well. See ortho.