Sorry for the delay, but I was out of the office over the weekend.
Cncerning your situation, the best way to protect your job is to request "reasonable accommodations" for your current disability. Even if you are certain that you are being harassed, by using the fact that you are being clinically treated for paranoia or depression as a means to try to get yourself transferred away from the person whom you believe is committing the harassment, you are also exercising your right to be free from disability discrimination under federal law, and the employer will be very careful about any thought of terminating your employment, as long as you are successfully performing the essetial functions of your job.
To this end, you may need your psychologist to certify you need for "reasonable accommodations" to the employer. Once this is done, you can simply return to doing your job, and then if the employer retaliates against you, you would be able to file a complaint with the Department of Fair Employment and Housing.
Note: you can find a database of "reasonable accommodations" that apply to employers and employees, at this link.
This may assist you in determining what you may need to successfully continue working.
Also, note that I am not discounting the possibility that you are actually being harassed and that your employer is ignoring the issue. Sometimes, however, you have to play it safe, and using your rights under the Americans with Disabilities Act may be the best way to do this in your circumstances.
Hope this helps.
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