Am I being discriminated against?

It sounds like you might very well have an employment discrimination case, under the federal Americans With Disabilities Act ("ADA").  That law bans discrimination against a person because they have, or have been treated for, any physical or emotional illness, if the condition doesn't affect their ability to do the job.

The problem with these cases is proof.  Once you make a basic showing, that you've been denied promotion because of the condition, the company will have a chance to show that the decision against you was actually made for legitimate business reasons.  You'll get an opportunity to prove that their "legitimate business reasons" were actually a sham, but sometimes that's not easy.