Thanks for the query to H.C.M. Forum.
Presuming that injury
was on the lateral part of left ankle.
As you got 18 stitches means injury was extensive so you might have got fracture
or ligament rupture along tendons or nerves underlying.
Since yellow bump may be a swelling with pus containing in it.
Inferior tibio-fibular ligament or lateral ligament got injury.
Without C T scan & Xray of effected part, not possible to evaluate the diagnosis.
Consult one more Orthopedic surgeon and get his opinion.