I'll try to include as much information as I deem relevant.
I just got back from vacation (driving tour of New England), and towards the end of the ride I felt some minor abdominal discomfort which I ignored until I got him about half an hour later. When I returned, around 4 o'clock, I passed a significant amount of relatively painless diarrhea.
A few hours passed and it happened again. The stool was so watery and so painless that I mistook it at first for gas. After that, more bouts of very watery diarrhea. I went to bed and it woke me up -- not once but three times (once at 6 a.m., once at 7 and once at 10, and I went to bed at 1). It's now been almost 24 hours and the bouts of diarrhea have yet to stop. I've taken two Imodium tablets about two hours apart, and it hasn't seemed to help. It's completely painless, it just doesn't seem to stop.
My abdomen has been making strange gurgling, bubbling noises, and I also began my period around the second bout, though I'm not sure if that's relevant. I also seem to be burping excessively (for my body, anyway), but again, I'm unsure if it's relevant. I'm an eighteen-year-old white female.
I'm home alone at the moment and I'm wondering if I should contact a doctor of it's something uncomplicated that I don't need to worry about.