gastro-intestinal problem

Hi, For the last 5-6days I am having some problem in the bowel movements. I am taking food and friut juices from the same place for the last 4 months. There is no change in my routine. I take food from a students' canteen and other things like fruit juice and boiled eggs from vendors. I am not staying at home, so whatever I take is from shops or canteens only. Initially it started with some leaky watery stool once in a day around noon time. Stool looks pale and I also observe some undigested food material in the stool. This condition lasted for 3 days. Now, the stool looks semi-solid with a fowl smell. It doesn't follow any time and it happens anytime in a day. This happens 2-3 times a day and usually immediately after taking meal. Initially I thought its due to body heat and I started taking butter milk, apart from taking fruit juice twice a day, which has been my daily routine. But it didn't subside. Moreover its becoming more uncomfortable day-by-day. I didn't notice any other symptoms or discomfort in the stomach like bloating and nausiatic symptoms. But, just before such forcible bowel movements, i feel some kind of mild pain around the anal region. However, the pain is not persistant and it becomes normal after the defeacation. Do you think its due to food-poisoning? Please help me overcome this problem as its disturbing my work and I want to get rid-off this as soon as possible.