my toddler won’t eat anything !!!

my son is 2 and he hasn’t ate a single thing today idk what to do !!!! he has days where he won’t eat much of anything but fruite and his pediatrician said it’s fine they get like that sometimes as long as he’s putting food into his body but today he just refused to eat anything at all should i take him to urgent care ?? he’s playing and running around normally i’m not sure what to do i’ve tried offering him food all day all his favorites including fruite and he takes a bit and spits it out…. any tips ???