Selective Eater

I agree with Mom F. Smoothies are an amazing way to get nutrition into children, and if you have a selective eater, call it a milkshake. :p

Two recipes I've used with even the pickiest eaters that have come into my house (not my kids, though, they'll eat ANYTHING) are:

1 banana
1 large kale leaf
1 cup frozen strawberries
1 orange, peeled and de-seeded
1 carrot
2 TBS toasted wheat germ
Half a cup water or lemonade
Blend until smooth.

Or:

2 cups chocolate milk (I prefer soy, rice, hemp or almond for nutrition)
1 banana
Half a cup of greek yogurt
1 kale leaf
2 TBS toasted wheat germ
1 TBS sesame tahini
1 TBS peanut butter
1 TBS ground flax seed

Amazing Grass also makes this GREAT product. It's a drink powder that's full of powdered fruits, vegetables and other nutritious things. They can be found here: http://www.amazinggrass.com/kidzsuperfoodchocolate.html

I'll throw a few scoops of the chocolate flavor in with the chocolate banana smoothie, and a few scoops of the berry flavor into the strawberry smoothie. You can also just mix it into milk like they say, and feed your son "chocolate milk". He may not like it plain, though, as it does have a kind of 'funny' flavor.

If "milkshakes" don't work, I suggest checking out these two books: Deceptively Delicious by Jessica Seinfield (http://www.amazon.com/Deceptively-Delicious-Simple-Secret...) and The Sneaky Chef by Missy Chase Lapine (http://www.amazon.com/Sneaky-Chef-Strategies-Healthy-Favo...)

Good luck with your little guy!

Since he is taking antibiotics, I would recommend making smoothies out of yogurt and frozen fruit. I often add other food to mine (e.g., spinach, kale) that my son doesn't even realize as the taste of the strawberries (our main ingredient) overpower the other tastes. You also can buy vitamin or protein powders to add to the smoothies for additional benefit.

Definitely need the yogurt! I really like the smoothies idea. Sometimes it is a texture thing not taste. Maybe let him have the smoothie for supper if he had a good lunch-then you can fix something healthy for your and the rest of the family. But have him sit with you while you eat. He might try it after awhile.
What about graduating to say just the patty and a side salad? Then graduate to chicken instead of beef.
We purchase frozen cheese pizza and then put our own toppings on it. It may not be the healthiest but maybe healthier than from restaurants. You could chop up veggies real small instead of big chunks and make it meatless.
You can also bake home made chicken nuggets-google recipes. Many use cereal and have him help you or watch you roll them. Maybe make a bunch if he likes them for a quick snack all week.
Peanut butter is good. You can make quesadillas with lowfat or skim cheese-the tortilla requires no butter like the grilled cheese. Serve it with salsa/quacamole. Actually, I ate a lot of chalupas while on Weight Watchers-corn tortilla-baked, not fried-beans, veggies, lowfat cheese. Or even a bean taco on whole wheat tortilla (my kids love to take these when traveling).
I also read somewhere not to worry about the daily but weekly intake. Their little bellies are much smaller and really sometimes, after two bites, they really are full.
Praying for a quick recovery!

Food is an issue at your house. Kids pick up parents bad habits. His diet was bad and you now have an opportunity to change it for the better. I have a sister in law who only eats certain things and does not eat vegetables etc and her child has all these hang ups and does not eat healthy. She now has IBS but of course sees no correlation between years of not eating anything healthy and her current problems.
You are setting the example for their lives. Buy and cook healthy food and do not have unhealthy stuff in the house and only eat out (or buy fast food)once a week. If he has been sick he does not need unhealthy fast food. Do not feed him fast food just to have him gain weight.
Offer healthy food three times a day and do not allow him to snack on unhealthy stuff or dictate what he eats in between. He is little and will do what you model. Be the parent and be a healthy one. It is time for both of you to eat healthy.
He will hold out and act pathetic for a short time but if you are positive and consistent he will begin to eat what is offered. Children adapt to whatever example they are given.