Lack of sleep

Lately Alex has been waking up at around 3 am everyday crying, hard. It started Sunday morning. At first we thought it was because of teething. She has her 9th tooth coming in. But then she has done this everyday so far. And its the same time each day with the same reaction, her crying so hard and so loud. We have never ever had to deal with a crying screaming baby in the middle of the night, so this is really hard. The second morning Doug got up with her, brought her in the room (which I didnt agree with) and tried to get her to sleep with us. After an hour and a half of tossing a turning, not one moment of sleep, he took her into the living room where she played until about 5 in the morning. Then the following night she did it again. this time Doug got up with her again and took her into the living room. She finally fell asleep after playing and eating at about 6ish. This morning she did it again. This time I got up, gave her paci and beary, turned on her music and closed the door. She screamed, literally, for about 15-20 minutes until she finally fell asleep. The whole time I was awake listening through the monitor. Since Sunday, we have had only about 3-5 hours of sleep a night.
About a week ago we switched her to whole milk. So the doctor advised to try switching her back to formula and then slowly weaning her off of it onto milk. We have started that and the girls at the daycare are helping as well. We are also wondering if she is having nightmares that wake her. But its weird that she wakes up at exactly 3 every day. We have given her motrin for any pain, gas medicine, water, milk, but still nothing. What is even more weird is that she has perfect days at the daycare, never cries, plays well with all the kids, eats great, sleeps at least 2 hours and has normal dirty diapers. The girls cannot believe the stories we tell them.
So now is another night I am dreading, hoping she goes to sleep. I never had to deal with a screaming baby. She has always been so good at laying down and going to sleep.