What Causes Increased Bowel Movement?

Question : Hi,
I am a vegan- I have been a vegan for 6 years. For the majority of those six years, I've had an average of 1-2 bowel movements a day, and they pass easily. Now, however, something has changed and I do not know what. For the past three months I have been having 4-5 bowel movements a day, mostly in the morning, and every one is explosive. I feel as though I do not have control over my body. For instance, I will be driving in my car on the freeway, when a bowel movement occurs suddenly. I then have to pull over IMMEDIATELY, or at least within three-five minutes, or else I'll lose it; it is VERY painful to hold it in for very long. My stool is either loose-form or soft-form. It is not oily. I originally thought that this was something (an illness) that would pass but now that I have been living with this for three months I suspect there is something that needs to be treated.