There is a place called Caravel Autism Health that has therapists with BCBA/ ABA degrees. You might try there. Is listed in Deerfield but they are hiring staff for Crystal Lake. Try them at (Phone number can only be seen by the question and answer creators).
Message me, please, if you need additional resources. I am in southeast Iowa and our BCBA came from IL and may have recommendations for you if needed.
Hope this helps!