Calcific tendinitis shoulder is a an acutely painful shoulder condition where there is calcium deposition in the shoulder rotator cuff muscles. This is usually seen on xrays.
There is a predisposing tear/damage/degeneration in the rotator cuff muscles which predisposes to dystrophic calcification (calcium deposit in dead tissue). This calcium can get released on and off into the joint predisposing to inflammation.
Rest, Ice and anti-inflammatory medications are the first line of treatment.
Intraarticular shoulder injections can be given for pain relief. But it is better to do Ultrasound/Image Intensifier guided needling/trephination of the calcium deposit and thereby breaking it into fragments.
If these measures do not work, mini open/arthroscopy techniques can be performed to let the calcium out.