Your employer is required to provide "reasonable accommodations" regardless of if you disclosed during the hiring process or not. The normal process is to go through HR. They will have you fill out forms that need to be signed by your doctor. HR will keep your boss in the loop. Just do some brainstorming based on your situation to think about what you need from them. If your job can be done from home, you could ask to work from home as needed. You could request to cut down your hours, take short term disability, reduce your responsibilities. It depends on how flexible your job is. The disability act defines "reasonable accommodations."