Unfortunately there is a stigma attached to People who don;t look SICK but are VERY SICK. I have been living with this for 20+ years.
I used to not disclose to a future employers during the interview process about my disability. If hired I would then disclose that information to the HR department and work with them for accommodations. and who else would need to know.

Legally you don't have to say anything. I don't. I do however have fmla for the days I can't work because of the pain. It covers serious medical issues and you cannot get in trouble at all for calling out when you need. You have to certify about every 6 months.

http://www.centerforendo.com/articles/workanden... better article to help you

http://employment.findlaw.com/family-medical-le... http://www.ada.gov/2010_regs.htm I put links going over both FMLA and ADA with you hopefully these help!!

Okay to your answer. Not all employers have FMLA. To be eligible for FMLA you have to be with that employers for over a year and they also have to have over a certain number of employees. They all do however have a way to accommodate people with disabilities the are required to due to the Americans with Disabilities Act. So your employer is required to make a reasonable accommodation to you. My employer is a bank so they meet the eligibility for FMLA. My boss reasonably hates me because I'm undependable. I'm healthy one day and in the middle of a flare the next. She told me I ruin the customer experience with my call outs, tried to move me to the back office from my current one in the front, threatened to fire me, and has put me on a forced leave for something that my work could reasonable accommodate. This is discrimination so I reported her to the EEOC. Honestly they can't fire you for your FMLA protected time the also can't discriminate against you for it. Every employer has to have something in place for accommodations so I recommend asking your employer what they have before you miss to many days and working through that.