Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
Fistulotmy means opening of the tract of fistula in ano. The feces has numerous bacteria hence the resultant wound gets infected and healing is thus delayed.
Another reasons can be specific infections like
tuberculosis, Crohns and so on which needs proof by
biopsy of the tract so that a specific treatment can be done for an earlier healing.
Hence I would advise you to go for refreshing surgery and request your operating Surgeon to send the tissues for histopathology.
Also do Sitz's bath in a tub with warm water, particularly after passing motion to clean off the fecal contamination.
Apply liquid
Betadine that is
Povidone Iodine 2-4 times in a day.
Change dressing twice a day.
Take multivitamins and minerals for helping early healing.
Hope I have answered your query.
Let me know if I can assist you further.