Hi, thanks for writing to HCM.
It is very common to find tense swelling, pain and numbness
in ankle injuries.
As the xrays have ruled out a fracture
, the only possibility in your case is a ligament injury
Generally, these ligament injuries takes around 3 weeks to settle down with proper immobilzation in the form of a brace or cast. So up untill that time, it is normal to have some swelling and numbness.
scan will rule out a serious ligament damage.
Consult an orthopedic surgeon and follow his advice accordingly.
Hope this information is helpful. Good day