Not sure if he's starting teething or what, but son has woken up at 430/530am today and yesterday and I couldn't get him to go back to sleep. He usually sleeps until between 630-730... He's also constantly wanting something in his mouth this morning and looks extra tired (even though he took an almost 2 hour nap from 0630 to 0815) and is fussy.

Do you all think it's teething? He's 16 1/2 weeks old. How long does it usually last?