Hello, Thank you for asking your query at DoctorSpring.

From your symptoms, the whitish discolorations are Fordyce spots. These are small white spots that appear in shaft of penis.

Amoxicillin or Tylenlo do not have a side effect of producing white discoloration on Penis. But, you also need to understand that some men have these spots as normal spots. They are present as a normal anatomical variation, they are not harmless and perfectly normal. you have nothing to worry about. Though I suggest you consult physician once.

Hope this helps. Please feel free to ask follow-up questions