Work cannot ask you why you are out...they won't know if you don't tell them. This should include coworkers, even if you consider them a friend. In my last job, I had two medical leave absences of 3 months each. They never found out, as I didn't tell them. Didn't share with anyone other than immediate family members. I've had a new job, and am stable, but I don't tell anyone there, either, about my illness.