Could be a couple of things.
Not knowing age, gender, or
sexualCauses of sexual dysfunction
Erection problems
Female sexual dysfunction
Sexual problems overview practice-- so ill list some out. [but you did title this Mr.]
Hemorrhoids. Perhaps the most
commonCommon cold. If they appear "meaty" it is likely a prolapse hemorrhoid.
If one is an elderly female who has birthed several children, rectal prolapse is an potential source
In regards to sexually transmitted diseases- condyloma is a another cause
If you are an elder