No sleep

My 1 year old was doing awesome on sleep. He would fall to sleep between 8 and 8:30 pm and not wake back up til 5:30 and 6 am. Now here lately he's been sleeping for a couple hours and waking back up and staying awake for over an hour to over 3 at a time. I'm beyond exhausted and have no clue what to do. None of my others done this. I need some rest especially being pregnant but don't know what else to do. I make sure he's ate plenty and I even hold him to try to get him back to sleep and it's not working :'(