At least your supervisor knows. My boss doesn't know. But, I'm lucky that if I tell him I'm not feeling well, he lets me go. I thought about telling him, but it's just kind of a strange situation. (It's a long story!) I asked my boyfriend what he thought about me telling my boss (he knows him also) & he didn't think I should. I just feel guilty leaving sometimes so I thought I should let him know, but I've never had a problem having to leave. One time it was during a very important day, and he didn't even mind then. Luckily, it's not that often. The last time I had to leave was back in Jan., and I can't remember the time before that. Maybe last summer? I try to suffer it out at work if I can so I can save it for if I REALLY have to leave.
But it does feel good letting people know. For a few years, the only people that knew was my mom, my boyfriend, & my best friend. I just told my dad in December. I'm gradually telling more people. It's hard, but I think it gets a little easier each time.