bowel movement question

Has this happen to anybody and sorry for the graphic description. 
    I am 15 weeks pregnant and over the past 2 weeks or so I have noticed that I have had diarrhea more often. And a few times I have noticed that there is white particles when i make a bowel movement. No blood or anything. I don't know if I have something seriously wrong with me. I have a dr appt next week. But, it's making me anxious tonight thinking and worrying about it. I'm going to call the dr tomorrow. But, I just want to know if this has happen to anyone and what was the cause.