Hi ! Good afternoon. I am Dr Shareef answering your query.
You have not mentioned the nature of minor surgery in the anus. Whatever surgery it was, there could be some fibrosis
resulting in minior to moderate anal stenosis which could resist passage of stool, and thus cause you to exert more pressure during defeactation.
Apart from the nerve injury
mentioned by you, application of more amount of pressure during defaecation could be a normal variant in this age group due to inability to exert required amount of pressure during the act because lax abdominal musculature.
However, if I were your doctor, I would not hesitate to refer you to a surgeon/gastroenterologist for a per rectal examination
and a possible colonoscopy
considering your age when a few pathological processes may be more frequent.
Till that I would advise you for a high roughage diet with plenty of liquids to make the bulk of stool soft, and to avoid laxatives as far as possible as a habit.
I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts.
Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef