Thanks for posting your query.
From description , it seems ligament injury
over knee and ankle.
If you are able to bear the weight on your limb without much pain then a bone injury
Now after 3 weeks if pain is severe ,I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management. You may get theX-ray/ MRI
of the area affected under his/her guidance.
In the interim,you can take anti-inflammatory drug like motrin
to reduce pain and inflammation. Avoid putting weight and rest well.
I hope this information has been both informative and helpful
You can consult me again directly through my profile http://www.healthcaremagic.com/doctors/dr-saurabh-gupta/64132
Dr Saurabh Gupta.