It might be a rotator cuff tear or supra spinatous tendinitis.need through assessment..Don't do any over head weight lifting exercise which may damage more.use Ice pack 2 -3times a day and any anti inflammatory medicine (if you don't have ulcer or any
kidney problem).
Consult with your nearest physiotherapy centre or a manual therapist.
Next Steps
rest and ice will help you
Health Tips
do not lie down on painfully side.