Hi there,This is Dr Basu, experienced Internal Medicine Specialist. I am here to address your concerns and provide great service.
You need a MRI scan of the knee to look for meniscal tear or any ligament tear.
That will cause severe pain as you described.
You should see an orthopedic surgeon for further evaluation.
In case of tear, you will need arthroscopic surgery for repair.Best wishes,It was my pleasure to help you today.If I have answered all your questions, Please rate my response Excellent (click on the 5th star).Please bookmark my profile for fast, reliable and authentic answers!This is the link to my profile:http://www.justanswer.com/medical/expert-mysticdoc/