E.M.
Try finding an at-home daycare if illness is causing a problem. I have been working with kids, mainly out of my home, for over 12 years and we very rarely have an illness that spreads through all the kids. I had 5 kids at once, along with my son, a few years ago and we never had an outbreak. I have worked in a couple of daycares over the years as well and some (not all) don't sanitize their toys or tables as well as they should.
If you could find a stay-at-home momma who will only take on a couple kids at a time, you will cut down the sickness greatly! I keep things extremely sanitized. My son brings germs home from school (which is just how it goes), but we keep it away from my 18 month old daughter and the little one I watch pretty well!!
Good luck!!