Hello and welcome to HCM,
An incision especially surgical incision heals to form a scar tissue along the line of the incision.
The scar develops along the incision site only and not beyond it.
Sometimes, the scar tissue may develop outside the incision site.
This is called hypertrophic scar
This is most probably what is happening in your case.
This occurs due to over activity of fibroblasts.
On the contrary this could be a recurrence of plantar fascitis.
Plantar fascitis is nothing but fibrosis
of normal tissue.
Conservative treatment is not usually effective.
You need to consult your surgeon for surgical removal of the tissue in case it is too uncomfortable and painful.
Thanks and take care
Dr Shailja P Wahal