75yo grandfather severe pain on both shoulder blades. mri,normal.pcp prescription norco+suggested pt.pain doesn't allow sleep at night.what can this be?

The back/neck : May be stemming from the Thoracic spine or cervical spine. Other consideration are other muscles/tendons/ligaments/fascia in the area.

Sometimes no answer: Often pain is difficult to blame on a specific cause. It's always better to try physical therapy, heat, massage, and mild analgesics such as Tylenol (acetaminophen) or ibuprofen. If it doesn't get better, continue to investigate a possible source. If MRI is normal, that's a good sign that there is no tumor, infection, or any other dangerous problem. Narcotics may help but should not be taken for very long.