baby sleep went to wack!

So just a couple days ago my 11 week old started sleeping 1-2 hrs at night and waking up from 8-7:30am that's his bedtime I haven't changed anything in his routines. He still takes atleast 1 nap a day because he fights his sleep. He use to sleep 4-5 hrs and it's exhausting because he is literally waking up almost every hour now! What do I do?! :( what's the cause of it? Before bedtime he eats off of both breAsts and takes his time!.