L.,
You need to go see your doctor. I'm not saying that in a "don't be stupid" way. I understand that some people really don't run in to be checked out for every little thing. It might be financial, don't really have a good doctor, or sometimes we are afraid of what things "could be" and that keeps us out of the doctor's office.
But seriously, you deserve to not have to be a slave to the toilet all day long! You need to get to the bottom of this even it just ends up being IBS (irritable bowel syndrome).
Call your doctor in the morning. Don't psych yourself out, just make the call knowing that you are going to start feeling better and be back to normal in a little while.
Good luck!