Have a deep pain above right shoulder blade, what causes the pain?

Many possibilities: The differential is long but here are a few of the more common considerations: referred pain from the cervical spine (particularly C5 which supplies some of the muscles of the scapula), intrinsic shoulder pathology (impingement syndrome, rotator cuff tears...), brachial neuritis (parsonage turner syndrome) and entrapment neuropathies (dorsal scapular nerve). Please meet with your doc. Good luck.