It might be coincidental that you picked up the stomach flu and hopefully this isn't indicative of how the remainder of your pregnancy will go. Our entire house just got over that stomach flu, but it only lasted about 36 hours.
As the above posters mentioned, be sure to get checked for dehydration, because it can creep up on you quickly. Take care!
My Dr said that Imodium AD and Kaopectate were ok to take for diarrhea. You definitely need to make sure your not dehydrated if the vomiting has been severe. Call your Dr in the am or go to the hospital.
I would go to your doctor or hospital and get them to check that you aren't dehydrated. It can be very serious for your baby... They should also be able to advise you on safe medication to take.