Legal Question in Employment Law in Illinois

You don't provide enough details but I will give you some basics that I hope point you in the right direction.

FMLA--Since you mentioned what sounds like a serious medical condition, you would have qualified for FMLA if you are a covered employee (worked for one year and 1250 hours for an employer who has 50 or more employees within a 75 mile radius). The FMLA would have allowed you up to twelve weeks leave, taken as a whole chunk or intermittently. Were you eligible for such leave? Did you take it? Were you denied leave? Did employer interfere with your FMLA leave rights?

ADA--Many conditions, though not all, that are covered under the FMLA are also disabilities covered by the ADA. The ADA provides additional protections in the form of reasonable accommodation. Reasonable accommodation could include job restructuring, modification of work hours, aides, or time off beyond the twelve weeks provided for by the FMLA. Did you ask for reasonable accommodation under the ADA? Was it provided? If no, why not? Did employer interfere with your ADA rights?

Workers Compensation: You mentioned that the panic disorder stemmed from work-related stress. Some work-stress claims could qualify for workers compensation protection. These are very difficult claims in which to prevail and the burden is high on the employee to show that the stress to which employee was exposed was unusual for the position.

Unemployment: In Illinois, if you quit a job because you have a medical condition, and your employer cannot accommodate you, you are generally entitled to unemployment.

All of these issues should be discussed with experienced and qualified employment counsel.

Good luck!