Excessive Weight loss and no idea why

A couple months ago i went to the doctor for loss of appetite due to excessive bowel movements of 4 or 5 times a day for about a week and then i was ok for another week and it started all over again. He ran blood work and took a stool sample, which both came back normal, so he diagnosed me with Irrital Bowel Sydromn. He changed my diet and that worked for me, for only a few days. I now have lost about 15 pounds and am begining to worry about what this is. If the blood and stool tests came back normal and ok, what else could be causing this and how can i make it stop?

Irritable bowel syndrome (IBS) can be caused by any number of things. There are steps you can take to narrow down the field of possible causes. Sometimes your body can become sensitive to foods which you have consumed all your life. With that in mind, try to stick with a diet consisting of only a few foods. (make sure to have a balanced diet consistant with the food groups) Avoid using spices, marinades, etc. If no progress is made, switch out one of the foods for something different. Also note that at may take days for your digestive system to normalize. Try and stick with one set of foods for a week at a time, then write down your results. With any luck, you will find some foods that agree with you. After that, you can introduce a new food or spice every few days.
I would recommend starting with chicken, whole grain rice, peas, carrots, apples, and water to drink. These are very 'agreeable' foods. Be sure to keep your water intake @ 6 - 8 glasses per day, and spread them out.

If this yields no positive results, perhaps it would be worth getting tested again. I had a friend who was diagnosed with chrones disease, but it didnt show up in his first test. Were you having syptoms at the time of your test?

Hope this has been of some help.