A.M.
the same thing with my 2 year old! One thing i have learned is to compensate with other things they like such as PBJ, chicken nuggets, yogurt, and definately use a multi vitamin . They are at an age where their appetites are going to fluctuate a bunch but it is ok! If they don't eat anything in a sitting just try again later. Try substituting with something they like but that is healthy.
One other thing- dont get him full on snack foods before a meal because then you know he definitly wont eat! Im not saying starve your kid before meals but if you do offer a snack it needs to be a small portion so they are hungry for dinner or lunch when the time comes.