Coffee, please....STAT!

I don't know what happened.  When I first went back to work almost a month ago, Jackson was doing so well.  He was pretty much sleeping through the night -- we would put him down around 8pm and he would sleep until sometime between 5-6am.  It was wonderful!  Lately, however, we are regressing.  We are putting him down at the same time but he's been waking up between 3-4am each night.  It culminated with last night when I was up with him about every 45 minutes or so between midnight and 3am.  Each time I got up, cuddled with him for a few minutes and he would go back to sleep, only to do it all over again within an hour.  Finally at 3am I decided he must be hungry so I got up, changed his diaper and got a bottle ready.  He finished only half the bottle and fell asleep in my arms so back to bed we went.  By shortly after 4am he was back in his routine of waking up and fussing which lasted until about 5am.  He fell asleep but at that point I was up for the day.  After all of that, I'm a complete zombie today.  And it's only Tuesday!  Honestly, I'm not sure any amount of caffeine will help.