Usually you have to declare any illness on your application form. Not to do so means that your employer usually has the right to get rid of you as you have not been honest. I always declare it and am open. I find it usually doesnt affect my work.
I'm so sorry about your experiences. I have always been open about my condition in the job interview itself even though our anti-discrimitation laws don't allow the employer to ask about disabilities. I figure it's better to mention it and answer any questions about it beforehand. I try to frame it in the context that I welcome challenges and know how to overcome adversity. I am careful not to exhibit a victim mentality.
One thing that might help you with future job interviews is to get involved as a volunteer with a local chapter of an organization that helps people with disabilities. For instance Muscular Dystrophy Canada serves people with MD but also with myotonia congenita and they always need volunteers. Then you can put that on your resume under community service and explain what got you interested in working with that organization. It's a much more proactive approach and makes it a positive, community focus instead of about you personally.
By the way, I would not use the skiing excuse even if it's partly true. Here in Colorado people struggling to make ends meet with the bad economy tend to resent those who have the money to buy lift tickets and ski all day. You never know what will prejudice a coworker!