Thanks for the query to H.C.M. Forum.
As you mentioned in your query , it seems that styloid process ( lower end of radius ) has fractured.
If this is , known as Colli's fracture, in my opinion it requires 8 weeks immobilization through plaster of Paris ( POP).
Swelling may be due to injury
Infection may be the other reason.
Consult another orthopaedician and get his opinion regarding this.