Suggest Treatment For Red Bumps On The Head Of Penis

Hi Doctor, For the past 6 months or so I have had these random red bumps that show up on the head of my penis. They are not itchy or painful and they are usually gone in around 24-48 hours. I have had 2 STD tests, the first was about 4 or 5 months ago, (Included HIV, Herpes and the other major STDs)(everything came back negative), and the second was about a month or two ago. The second was only a herpes test, it came back negative as well. I went and saw a dermatologist a couple weeks ago but the bumps were not present at the time. I explained to her that I ve only had these outbreaks a handful of times and they never last more than 24-48 hours and they go away. I showed her pictures that I had taken and she said it doesn t seem like herpes by my description and the pictures. Im kind of curious as to what it could be without going online and it saying that I have AIDS and cancer or something.