I think you should go for a follow up checkup to the respective surgeon who did your fissure surgery and tell him/her about all your complaints. He can suggest you better solutions because he has complete history regarding your concern. This is the best you can do!!
Still If you wish to follow online treatment I have mentioned some medications underneath, You can follow it.
Next Steps
Milk Of Magnesia 1 spoon to relieve constipation
Citrucel (Sucrose) Oral Powder
Anorelief Cream - to be applied on the affected area where pain occurs.
Health Tips
The milk of magnesia syrup is to be taken when required not daily otherwise you might land up having diarrhoea.
Anorelief Cream is also to be appiled when required.
The Citrucel Powder can be taken on a daily basis.
Despite of all the medications given by me if your problem doesn't resolve then please consult to your respective surgeon who performed your surgery.
Every person responds to different medicines differently so always take a caution before taking any medicine.
Hope Your Concern Gets Resolved!!