I am like you, it's very hard for me to do it. I was in the hospital, they thought they needed to remove my gallblader and I had to call my boss from the hospital. When I called I was so nervous that she would think I was lying even tho I was not, and I really could not just leave the hospital and go to work in that shape. I have a labour job and could barely walk but still felt like that. My voice was all quivering and nervous.. ugh. I hate people to think I am not reliable or worse lying. My boss was very understanding tho.

But you have not taken one in so long, and people get sick, other things happen and life goes on. It's expected that once in a while things will happen. So try not to worry about it. You deserve a day off for this. Odds are your boss has taken a sick day herself sometime.