Thanks for asking me to respond to your question. You may be having a SLAP tear or a simple labral tear. The shallow socket of the shoulder joint has a cartilage extension all around called the labrum. At the top end of the joint the biceps tendon gets inserted into the labrum and the associated bone. A year in this region is common in those who do overhead racquet sports like badminton. I suggest you take pain meds and rest your arm, that is avoid badminton for a couple of weeks. If pain still persists you may need to have MRI scan of the shoulder joint done to detect the tear. Good luck.