thank you for your query.
peri anal abscess
is a very painful condition and since the area is a dependent part,it takes a long time to heal also.putting a seton stitch is required when the abscess has converted into fistula.
In your husband's case, the seton loop will slowly cut through tissue inside the loop while scarring behind the loop, essentially "pulling out" the fistula.hence the continued pain and malaise
i would advise to-
-take atleast three 'sitz baths' per day, whereby a small basin is filled with warm water (and possibly, salts) and the affected area is soaked for a period of time.
-continue the anti-biotics
-if the pain is severe,you can use pain killers.
-take loads of rest
the symptoms will come down in few days.
wishing you good health