Hi Lilly,
Here is the link to Illinois on this site.
Illinois Search Resources
It sounds like a fairly open state and possibly has a registry that you can sign up for.
If you come to a brick wall you should petition the courts based on medical needs to open your complete file. Best to have a doctors note stating your illness etc. You can always hire someone to do the searching for you if you can afford it. There are search angels that will help too.
The court opened my files after I was dx with rare disease after a heart attack and stroke.
Good luck,
Dickons