Suggest Medication For Hard Pimple Like White Bumps On The Penis

maybe a year ago I had hard pimple like white bumps under head of my penis. Dr said it was a fungus so prescribed me cream and it cleared up. Twice now in in same spot and now another under head of penis I got clusters of blisters, start clear and turn white before breaking and clear liquid drains. Put in the right position they are noticeable but dont really hurt or anything. When they start it kinda itches and then nothing. Is this an STD.?