I have a son who was found to be color-blind. The only way to tell for sure is to take him to an optometrist or ophthalmologist who will do a specific test.
As for me, I already knew it ran in the family. In most cases, the mother is the carrier, and the males will get it. My great grandfather happened to be color-blind, and it was supposed to effect the grandchildren, but my grandmother had only daughters. So they became the carriers, and subsequently, their children (like my brother) were diagnosed with it. Now, a couple grandsons have it, as well.
Some are found to be only color-blind to certain "shades." My son or brother cannot see red or green. Since my son grew up, he has had to have someone ride with him, if he goes into a section of town where the red-lights are sideways.
So, if you have any more questions, let me know, and I'll try to be of more help. I felt so bad for my son, and my brother. But when the teachers knew, they allowed them to "miss" in class when it came to colors.
EDIT: Your son may or may not be color-blind, but a special test will determine that for sure. If he is, he will adjust. My son and brother both learned how to tell the "shading" difference between the red and green as they grew older. My cousin with the "shade" colored blindness... he just thinks certain clothes look awful on him, when they are actually complimentary. ((((smile)