Baby sleeping 9 hours only at night and wanting to nurse (xp 12-24)

camedowncrushing

DD (15.5 months)  has never been a great sleeper, but shortly after I night weaned her at 12 months she was sleeping about 10-10.5 hours at night.  She would sleep another hour to 2 during her nap. 

Three weeks ago she started waking in the night .  She would cry, and ask for milk.  I wouldn't nurse her, and she would get really upset.  Eventually (an hour to two later) she would go back to sleep.   She would then start her day at 4am.  She is totally crabby in the morning about an hour after she wakes.  She is clingy and tired and wants to nurse all day long.  She will nap at 7ish for a half our, and then around 1 for an hour. I know she needs more sleep, but I don't know what to do.

I have tried Ferber for the night wakings, and the early rising without success.  I have let her cry it out without me going in there for up to 45 minutes, and she just screams.  I then give in to get her and nurse.  I just feel so awful.  This morning she woke at 3:30.  I checked on her to make sure she was okay, and just told her it was sleepy time.  She screamed and screamed for 45 minutes. I thought she was going to throw up.  

I was hoping this was a short phase, but it has been 3 weeks.  She did have a dr appointment right at the start of this, and I mentioned that we had a rough couple of nights.  The pedi checked her ears, and they were just fine. 

 Should I be worried that she isn't getting enough sleep?  Should I just suck it up and get up at 4?  Is this common?  Any advice is appreciated.