Hello
welcome to health care magic, I have gone through your question very diligently and I really appreciate your concern.
itchiness and burning sensation after bowel movement might be related to hemorrhoids,
fissure in Ano or inflammation of rectum or anal canal also known as proctitis.
You should follow these measures for symptomatic relief
you should avoid constipation by taking of laxative or stool softeners
Have lots of fresh fruits and vegetables and
dietary fiber supplement
You can use anaesthetic ointment like lignocaine for pain and burning.
Sitz bath twice daily.
Multivitamin and
calcium supplements with antiacidity medicines like
pantoprazole or ranitidine for 7 to 10 days.
sperm you are talking about could be urethral discharge or inflammation of the urogenital tract, get your urine tested for culture and sensitivity test and you may require a course of antibiotics unfer medical supervision.
Hope this answers your question.
Best wishes