Thanks for posting your query.
According to description it seems to be soft tissue injury
or ligament injury
I suggest you to consult an orthopaedician nearby for a detailed examination.
In the interim,apply ice packs to the affected area, elevate the limb , give compression by crepe bandage but not to tight.
He can take anti-inflammatory drug like motrin
1 tablet with food as and when required (upto 4 tablets daily) to reduce pain and inflammation. Avoid putting weight and rest well.
Wishing you good health
Dr Saurabh Gupta