If he's only been feeling better for a week, I wouldn't push too hard on the foods he'll eat. This age is typically very conservative about what foods, flavors and textures they are willing to eat anyway. And they tend to eat far less than parents can believe will sustain them. But toddlers often need very little food unless they are in an active growth spurt, and many nutritional researchers believe this eating-resistant stage is a way humanity developed to protect toddlers from eating dangerous plants, berries and spoiled food.
So make a point of visibly enjoying a variety of foods yourself (don't make too big a deal of it), and put only tiny amounts of a variety of foods in front of him at mealtimes. Use a large plate so the food looks like even less to him. Use a small glass for his milk to make it look like even more. Suggest that he eat just one/two bites of each food you offer, then allow him to drink his milk. It is actually pretty nourishing. Give him a daily multivitamin, and maybe a lemon-flavored fish oil so he gets plenty of Omega-3 oils for good brain and nervous-system development (Carlson makes a good one that my grandson likes).
Another strategy that many parents find helpful is to put out small, attractive plates of cut up fruit, whole-grain crackers and peanut butter or a yogurt-based dip, cut up omelet or other healthy foods for him to graze on during the day. Keep quantities small to avoid waste and keep him from feeling overwhelmed. You might also be able to poke occasional bites of food into his mouth while he's distracted playing.
It's fine for you to gently urge your son to try just one more bite of something, as long as this doesn't turn into a major power struggle. He may be a sketchy eater until about 4 or 5, and this really is pretty normal. My grandson is just suddenly turning into a hungry boy – he's just about to turn six. His parents could hardly believe how little he actually needed over the past few years, but he always had enough sustenance to play, grow, and sleep well.