What happened?

What happened to my sweet and happy little boy?!?!?! This past week, he has turned into a crabby, whiny, cranky and clingy little baby. He decided that eating is overrated. He doesn't want you to put him down when we get home. He won't play by himself anymore. He spends most of his waking hours whining and with his head down and butt up on the carpet. I would say that it is attributed to teething, but he is only getting one bottom tooth (that I see) and he never acted like this before when he got four teeth in a matter of two days. I bought him some Pediasure yesterday, which of course he liked. I have to get some sort of nutrition in him. I don't really know how much to give though. I guess I should call the pediatrician and ask. I want my cute little cuddly baby back!!!! :O(