I'm not sure if this is the right subreddit so if this doesn't belong here please point me in the right direction.
My girlfriend worked for a private school in Illinois. She has bad asthma and had been to the ER twice already this year because of that. She told them about that before she started. A couple of months into her job she had to go to the ER again on Friday 7/8/22 because she couldn't breath. She was sick the previous day 7/7/22 with an upper repertory infection, she called work both days before she was supposed to start to let them know she was sick. She followed up with emails the following Sunday (7/10) and Monday (7/11) letting them know ahead of time she was still sick and not able to work. She also put in her two week notice at that time. They never responded to either email.
On Wednesday morning her boss called and asked why she no called/no showed and had to call the school immediately. She called and explained she was still sick and didn't tell anyone because no one has responded to anything she's sent since her first call, Thursday (7/7). The next day (Thursday 7/14) her boss finally responded with a very snarky email that ended with the boss thanking her for her work. She also received a voicemail the following Sunday (7/17) from an assistant manager asking if she was coming in to work that week.
On Sunday (7/17) she received her 'closing email' from HR.
Where it gets bizarre is last month she got her hospital bill and it said there was no insurance coverage, despite having insurance from work because she already payed July's premiums. Insurance said her company went out of the way to call them and back tracked her termination date to 7/6, two days before she went to the ER, because they said the last day she was physically at work, so was her termination date. Even though her boss was calling her a full week after that (7/13) asking why she wasn't at work–insinuating she was absolutely still employed at that time. Work never let her know why she was terminated. She let them know the day before each work day that she wasn't able to work because she was still sick.
They went out of their way to back date her insurance, even though she paid for the month, just to be spiteful. Is this legal in Illinois? Is there anything she can do or does she have to pay this $3,000 bill because they were vindictive? How could she have been terminated 7/6 even though they were still calling her to work on 7/13 and was never told she was fired besides her exit email from HR on 7/17?