Sorry to hear about your daughter, hopefully they will figure out something soon. The not knowing what is wrong is probably the worst part of it all. My son was sent to the hospital at he age of 2 months and it took a while for him to to get the diagnosis, but after that at least you know how to treat the problem. I can also relate to the long hospital stays, my son spent the better part of his first two years in the hospital an has regular visits due to complications. I have built many a terrain piece in the hospital, and played some excellent zombie games with the boy as well.
I hope that you and your daughter hang in there, and something gets worked out soon. It's good that she has gotten to do some fun things, the hospital can be dreadfully boring.