I am 18 now but i have had these white spots for 2 or 3 years, its just that only now i am really starting to freak out about it.the picture might not be that clear but these spots are really tiny and on the left side of the opening.
So, the general rule with something that has been in place for up to 3 years is that these are a natural development to your penis.
There are several things they could be - these develop with the onset of sexual maturity.
What you have are not typical to the type of things that can develop on the head of your penis - but my suggestion would be these are natural.
If the opposite were true, and these were caused by a problem condition, they would either have multiplied or continued to have developed in size, I would suggest.
If you wanted to be 100% certain you would need to get a Urologist to do a visual check on them.