Every few months since last August I've had little white spots that appear all around the head of my penis. Been tested for STD's all negative, dermatologist said it was a yeast infection. Gave me some ointments that get rid of the symptoms but it keeps coming back. Any ideas? Also makes my urethra itch.

You may be having sex with a person having a yeast infection, thus it returns, have you told all of your sex partners about this ? And allow them to clear it up ?

Have you spoken to your doctor about possible other causes,
Age, other health issues and poor hygiene are common causes in men. If you are not already, good cleaning morning and evening may help. Try to control dampness.