Loss of Bowel Control with little or no effective warning

I woke up one a.m., was late for work, skipped breakfast and had not eaten in over 15 hours. Without warning, I got a sharp pain, ran to the bathroom and didn't quite make it. I was able to clean up the "mess" to an acceptable degree, but much to my chagrin, the same thing happened 2 days later. I took Immodium for 2 days in a row because I was scared to death. Now, I'm freaking out. I can dress casually at work, so I've taken to wearing long blouses and now I bring extra undies and pants in a gym bag. What's up with this? This is totally new. Well, at least I've stopped falling down. This is getting a bit complicated for me. I have no virus or anythinhg. Is it meds? Is it a sympton. It's sporadic and doesn't seem to be involved with the actual food I eat. Thanks to anyone who can help me with this horribly embarrassing problem.