Thank for asking to HCM
I really appreciate your concern you have asked "Why does this happen at this age? and you did not mentioned the age here, constipation
some times cause such symptoms and because of this the rectum
may get the fissures and some time it gets the infections if I would be your doctor then I would treat this with the following medicines
1) Tab Cefdinir
300mg twice in day
2) Tab Policresulen ointment to be applied intra rectum
hope this information helps you, have nice day.