Your doctor will check your skin and make a diagnosis based on where the bumps and pockets are, and how often you have them.
He may also ask you questions, such as:
You usually don't need any tests to confirm a diagnosis. Sometimes, in order to rule out other kinds of infections, your doctor will take a sample of the pus and send it to a lab for analysis.
How long ago did your symptoms begin?
Are the bumps giving you pain?
Have you had these symptoms in the past?
Have any blood relatives had this problem?