Picky Eater

my son is almost 3 and has been a picky eater since he contracted hfmd from playgroup. before , he ate basically everything , from complete meal (rice, protein , veg) , snacks and all. but after the hfmd episode with ulcers in his mouth , he just didn't eat like before. then we realised that maybe his appetite has decreased as he was still still adapting with sch at that time. teachers would feedback that he didn't eat much or at all. I did trial and error of cooking different food for him and realised he loves fried rice. so I made him fried rice with different ingredients inside every day. sometimes he just wants plain rice so I'll just let him eat plain rice. he eats plain rice with a lil soup at sch and manages to finish it teachers say. although seems like pitiful , I don't mind as long as he eats. he drinks full cream milk twice daily so I make him eat rice even if it's plain. once in a while , snacks or biscuits. unless he requests to eat fast food like mcd , we normally won't buy it. cut down on the snacks if you can.