We're in about the same boat with boys around the same age and I'm about 9 weeks along. I have been having a hard time with this pregnancy with severe nausea and throwing up, but I also was getting quite a bit of diarrhea. It was weird to me because pregnancy normally slows things down and causes constipation. I thought it was because I wasn't eating much and when i did it was crackers and such and my body didn't like it. It stopped for me about a week ago, but I had quite a few episodes of it and thought it was odd.
It seems like it would make sense to occur since our bodies are not feeling well and adjusting - the same irritation that is making moms throw up could make our bodies want to reject the food in another way of getting it out quicker through diarrhea. Just try to stay hydrated (easy to say, I know!)