I just started taking the antibiotic Doxycycline for my strep-throat if it's any consolation, but just like the title says, I just noticed these purple/red bumps on the head of my penis. They are no where else to be found. There's about fourteen, ranging from less than one MM to less than four MM. Let me be clear by saying they are raised bumps. They do not itch. They do not hurt. It cannot deal with anything being sexually transmitted. And, like I said, I only just noticed today.

Could it be because of the anti-biotic or is there a possibility it is something else?

Also, could they be contagious or dangerous to others?

Thank you in advance.