He's turned very pickey these last few weeks. There's a reason why they suggest a certain amount per day isn't there?
Missed this post.. the sudden picky eater is also a sign of gut imbalances... the "bad" bacterias tend to make the body crave starches & sugars, so many kids with gut imbalances start to limit their diet to show preference to those foods, kwim?
If you're really concerned about nutrients though, I would seriously look into juicing. Get a good quality juicer (the Omega line is amazing, but even something like the Jack LaLanne would do) If you're on a budget, look for one on Craigslist or other online classifieds. You can juice for your Ds - greens, broccoli, carrots, beets, celery ect and be sure to add some tasty fruits like apples, oranges ect. The sweeter fruits mask the healthy, therapeutic veggies. One full cup of fresh pressed juice can give him all his vits/nutrients for the day (incl Calcium)
My Ds1 *loves* his juice.