My son is a picky eater, any advice?

Tweet

My son used to eat so much, when we started him on baby food he loved the vegetabels. Once he ate regular food, he would never touch baby food again. He was eating everything, he loved chicken, pasta, macaroni, and much more. About a month ago he started not eating that much. He will only take a few bites of things, but he can eat GOLDFISH crackers ALL DAY long. I know they aren't healthy at all but he won't eat anything else, i've tried everything. Now when he sees the color green he won't touch it. He will eat maybe a half of a hot dog and goldfish. Should I be concerned? Should I take him to the doctors? Is there any methods to use to try and get him to eat more?