You have to take the cat to the vet. Chances are it has an ear infection, which will require medication. Do not go sticking things into the cat's ear, trying to remove the pus. Make an appointment with your vet as soon as possible, and let them take care of it.
An earache or pain in the ear, which may be severe, or a sudden decrease in ear pain, followed by ear drainage of clear, bloody, or pus-filled fluid, hearing loss, or ear noise/buzzing.
Pus filled cavities are called abscesses and are treated with surgical drainage of the pus and antibiotics.
pus-filled, pus
If you were pierced by a professional piercer (ie. with a needle) then go and see your piercer, if not go and see your doctor.
Boil
Fluids not pus! eughhh!
SuHo
Empyema, Abscess
That is a very typical finding.
A pustule is a small accumulation of pus, either in the epidermis or dermis, or inside a pimple.
otopyorrhea = purulent otorrhea = discharge of pus from the external ear
Semicircular canals: are the fluid filled structures in the ear, which are involved in balance.