Hi,
Thanks for posting your query.
It might be due to bursal inflamation or
tendinitis.There might be possibility of ligament strain or tear.
I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management. You may get the X-ray/
MRI of the area affected under his/her guidance.
I hope this is helpful to you.
Regards.
Dr Saurabh Gupta.