Stress belly (TMI)

Im 21 and I'm moving across the country by myself this weekend [insert hyperventilating sounds here] so, naturally, I'm nervous. I'm stinkin excited, but so so nervous. Also probably subconsciously extra nervous. 
For the last two days I've been plagued with numerous bouts of diarrhea, sometimes even up to 3 times an hour. I'm certain it's because of my nerves.
If I can help it, I'd rather not take medicine to make this go away. But I'm starting to get pretty desperate. HOW do you calm your belly when you're making a big change? What can I do to reassure my body that everything is okay and we don't need to completely deplete our resources every damn hour?!?!
Please help.