Asking about your health conditions is illegal in a job interview in the United States. The next time an employer asks you such a question ask them why they are trying to ask you illegal questions. The only exceptions are jobs that require special security clearances or the use of firearms. But you would know if you were applying for such a job already.

I'm sorry that you were discriminated against. I'm wondering if they found references to your illness on a Facebook page or something like that and went digging.

I would never ever ever disclose my bipolar to anyone unless I was legally required. I don't want to hear about my coworkers hemorrhoids and I am sure they don't want to hear about my mania!