I've noticed this tiny dot on my penis for 3 months. It doesn't make me hurt. But I'm very worry about it. Is it related to any disease? What should I do?
Most likely what this can best be described as is a skin imperfection - that is it has not developed in the normal way, or something has caused it to be like this.
Simple causes can be something like you have picked, scratched or pulled out a hair and it has not healed as it would have done. It could also have been a bodily wart that you removed in the same way when it was first developing.
I would first of all treat this with a combination of Liquid antiseptic then a Cream antiseptic - use one one day followed by the other the next - treat it in the same way you would an insect bite.
Read the instructions on the Liquid Antiseptic and follow the detail on how to use it. My suggestion would be you apply these only once or perhaps twice a day for 3 weeks and see if it heals …