Thank-you for your question about your budgie's head. Could you please answer the following so that I might better help you?
-Is your bird a budgerigar?
-How long has he had the problem?
-Did he recently go through a moult?
-Do the dots move?
-Does he rub his head a lot?
Is there any chance that you could take a picture and send it via the tree icon on the toolbar?