Growths on shaft of penis

Hello,
A few months ago, I have noticed growths on the bottom of the shaft of my penis while shaving.
I immediately went to the doctor and gave urine and blood to test if there was anything that i might come up
positive for. (The doctor looked at the whart looking bumps forming and said it didn't look like any STD's. Almost
like it's been there awhile).  Well the test came out negative on everything. The doctor told me everything was normal.
With this I was satisfied and thought nothing of it.  Recently I have noticed new growths as if they are spreading.
They do not itch, irritate, or bother me at all.  Just the growths keep multiplying.  It doesn't look like a pimple, but it's definitely the size of a pimple with darker shade than my skin.  I needed help identifying what this is! someone please help!