You might want to consult an attorney, especially one who deals with labor law, and disability cases. FMLA might not be the best option, since it is unpaid leave, which you said is financially impossible. There are other options and programs. The Americans with Disabilities Act says that an employer must make reasonable accommodations for you. For example, I am a locomotive engineer. Especially early on the single sided deafness made it hard for me to tune out the locomotive noise, and concentrate on radio instructions. The company got me a David Clark headset, like airline pilots use.
There may be other programs, which could be beneficial. The cold shoulder from your boss should not be taken lightly. This is why I recommend learning about what rights you have. You might also contact the HR department, or even the employee assistance program. There is no good in loosing your job, especially if it can be prevented, by the company knowing what you are going through.