diarrhea at 34 weeks pregnant??

Sorry ladies but this is concering me, I'm almost 34 weeks pregnant and for the past 6 days I've had diarrea 3/4 times a day, I get very bad pains every time I need to go and it passes as soon as I've been. I've not ate anything different nor have I had food posing/viral as my children and husband have eaten everything I have and are completely fine. I lost my mucus plug about 2 weeks ago. I'm not on any laxatives. Could anyone think of what this could be please???