HELP!!!

I need advice! My daughter, Kallie, has been terribly sick for about a month now. It started with vomiting for two weeks. She had to spend one night in the hospital for dehydration. Then, it moved to the other end (Not to be too descriptive). That has been going on for two weeks. Now, she has a terrible cough and a fever. The doctor's say she has a poor immune system right now and is just catching everything - possibly because she may have had mono earlier in the year. On top of this, she has been pretty sick all school year with sinus issues. Anyway, I called the babysitter this morning to say that the kids would not be coming. She went on to say that everyone in the daycare has been more sick this year, including her, and that she feels that it is because Kallie has been so sick. This really made me angry because I don't feel as though it is Kallie's fault that everyone else there has been so sick. This has been one of my personal most healthy years so it doesn't seem that she is giving it to everyone. I am really thinking we need a new babysitter. If she is going to pin this on a two year old when she has twenty kids there or so, it just doesn't seem like the right place for us to be. In the mornings when we arrive there isn't a "hello, it's great to see you" or anything like that. They are just very unfriendly to us much of the time and I'm just not sure why. I am just feeling like I am drowning in a mud puddle or something. I don't know what to do about the illnesses and how to get her healthy and I don't know what to do about the babysitter. I know that I have really rambled and not put my sentences together in a very organized fashion, but I am writing this as a call for help. Does anyone have any suggestions for me?