Thanks for the valuable question. Any new finding that you seen on your penis can cause anxiety for man. It is good that you show this to your normal physician. A treatment can be prescribed, if needed only after physician examines your skin along with detailed history. There can be many reasons that can cause the rashes like Pearly Penile Papules which are tiny bumps that can be pink of white or sometimes even red but not at all itchy. This condition is found in about ten to twenty percent of men but not identified as STD. They can stay within your skin for many years. If it just appeared and doesn’t surround the head of the penis then it can also be a STD. Better consult your doctor for the right treatment and always glad to be of some help to you.