I've got a bald spot that oozes puss about once a week. It's about 1 sq cm. How can I cure it?

Question

Sorry, it's on the back of my head.

Answer 1

It could be ringworm.  An anti fungal med would help it.  

If it is ringworm, it is very contagious.  Wash bed linens often.  Don't share combs or hats either.

see the link below for more info

Answer 2

That's localized suppurative infection. That's an abscess. Have it incised by a surgeon. It has become bald because the blood vessels supplying blood to that tissue have inflamed.

A minor surgery will be done for that if the prescribed antibiotics are not enough. Refer to a doctor. You never indicate its location.