I have a sebaceous cyst that is bleeding. ?

Cyst: Sebacious cysts usually don't bleed. They are filled with cheese like material that occasionally can get infected and turns into pus. If it is bleeding, it needs to be examined as there may be something else going on. Pressure to the cyst for the time being may help stop it, but seek medical attention promptly.

Treat before infect: You should have this examined for possible excisional biopsy.

Unusual: Can bleed if the infection ruptures thru skin but you may want to have it seen to make sure it is just a cyst. If so, a surgeon can excise it for you