We had illness, and of course teeth. He's lost weight and his pants that he finally grew into now are too big again

And he just doesn't want to eat. He doesn't want to sit in his chair, it's hit and miss. He doesn't want anything he used to mow down.
Is this those final two teeth or is it some new fun and wonderful phase we are embarking on at the age of 2?
We don't push it (I don't push it I should say) and really don't make a huge deal over what he is or isn't eating.
But it's getting worrisome to me a bit now. Can't help it.