Hi V.,
Have you taken her to a doctor?
My son was getting sick every third week. After a few months his breathing started to appear like it was quite labored. I finally took him to the doctor and he was borderline walking Pneumonia. We started with breathing treatments. First was Albuteral (spelling?) The something that started with a B. Nebulizer form. We did this from about Oct - Dec. Then we had to start back up again in March or so and stopped when school was out. He was fine for about two months and has started with the stuffy nose thing again. His breathing (chest) doesn't seem to be an issue this time.
As for the Day Care being clean. Well, it might be clean, but it just takes ONE infected hand to touch one item and your child to come right behind the infected one and touch the same thing. I know. It is hard to believe. But look at how many children there are, and how do you know how many people they come in contact with when they get home or.... how many people their parents or Guardians have come in contact with...
As for building her immune system. That will just take time.
As for helping with getting sick, I always like trying natural ways first or in assistance to what a doctor gives.
When it seems like just a cold, I start with a sweet Echinacea tea for my little guy. That with a good night sleep usually takes care of it or at least lets him rest better. Do some research on Natural Immune Boosters, see if any of them fit your needs. I don't know where you are located, but look into your nearest health food store. They are full of information.
If you have not been to a doctor yet, you may want to check in with them about this situation. Better safe than finding out later it has been walking pneumonia all along.
I felt real small after that.
These were the things that have worked for us.
I wish your daughter a speedy recovery and will keep her in my thoughts and Prayers.