B.B.
it doesn't ever stop! my 18 month old still gets REALLY picky about food, some days he'll eat loads of veggies, other days he won't eat anything but bread and noodles. i recommend making zucchini bread with whole wheat flour. i double the amount of zucchini and use less sugar, and that way you're sneaking in some veggies and he doesn't realize it. i've heard you can make it with other veggies too, like broccoli, but i've never tried. i give my son lots of fruit, so he's getting some fiber and nutrients. really really steamed mushy carrots are good too. just offer him lots of variety. even if he only eats a bite here and there, he's getting something in his system.
my mother in law told me my husband at about 2 1/2 went through a phase where he ONLY ate peanut butter and jelly for weeks, and she asked her doctor about it, and he said "just be happy he's eating something." i know it's hard not to worry but he'll be ok. it's cheerios now, but it'll be something else later. Good luck!