Thanks for posting your query o Health care magic . What I have understand your problem and find that it could be anal fissure or haemorrrhoides .these two are common in person passing hard stool or having constipation . I dont thing it as Staphylococcus infection .If you are thinking about infection you need to collect dischaarge or ake a swab from that lesion ain a sterile container and send it to Microbiology lab for culture and sensitivity testing . You should consult to a general surgeon for local examinaion and take treatment accordingly . thanks .