My body has changed and no one has the answer

For 52 years I have been able to eat anything and everything. I weigh the same as I did in High School. Now I experience diarrhea 2-5 times a week even when I watch what I eat very closely. No spices like Jalapeno, Chilly power, Serrano
or similar peppers. No undercooked onions. No green peppers, or gold, or red. Dairy seems to be ok. If I eat high sugar content foods it may be fine one day but more often than not the sugar will kick off any amount of imbalance that my stomach is experiencing. I can eat chicken cacciatore one evening for dinner without a hint of trouble yet I will experience diarrhea at lunch 2 days later. Many fast foods will bring on this problem without fail.
If I drink Yalkurt (a probiotic) every day AND watch what I eat I may go as long as 7-10 days without a problem. My doctor prescribed Belladonna/Phenobarbital and it has some positive effects but still no cure. This obvious issue is that something has changed in my digestive tract. Either something is missing or in excess or generally not functioning correctly. I had been prescribed an acid reducing medication which I thought was providing relief (the first few days). After a few months I stopped taking it and felt better right away. Now the trouble has returned. For over 2 years this problem has been on and off with very erratic and random timing. I have kept logs of what I eat, how much sleep I get, even tried to record a stress value for the day. None of these efforts have revealed a pattern that defines a specific point of origin.
I can feel fine for days then, 30 to 40 minutes after eating the wrong food, my stomach will begin to gurgle. If I notice soon enough and immediately take Imodium (immodium) I can sometimes get ahead of the diarrhea. Typically when I am going to experience troubles it will appear within 1 to 1:30 hours after eating. The Imodium (immodium) can turn it around just as fast.
I have tried taking 1 Imodium (immodium) per day as a preventative measure without success. I have been tested for all sorts of digestive tract issues. All of this testing reveals no definable troubles. I am hoping for some sound medical advice before I begin to explore the crazy holistic world. I should not have to live on pills to keep my food from attacking me.

[remar]

This sounds like it could be irritable bowel syndrome. Have you seen a Gastro Dr yet? It might be a good idea to see a specialist to find out what's going on. Remar

[whyme704]

Some how the diagnosis of IBS just doesn't cut it for me. IBS is simply a catch all phrase for "we don't know what is specifically wrong but we'll log it into this cubby hole called IBS" Something has changed in the way my body digests food. Either this can be corrected or my diet can be altered to avoid the irritants or ??? If medical science in general has no idea what to do with this problem then point me to someone who is sincerely interested in solving this issue. There must be a pharma company who sees potential a cash cow in providing an answer to this common issue.
Yes, I have spent thousands on all kinds of testing. So far I only know what it is not, with no answers as to what it is or how to move forward from this point.

[remar]

This has got to be so frustrating for you. There has to be an answer as to why this is happening. You did mention"when I eat the wrong foods" you have the stomach problems. You mention cutting out a lot of spicy foods but what about wheat, soy or anything that has gluten in it? Something is going on and I truly wish I could be of more help but I just don't know what it could be. I hope your able to get answers soon. Take care. Remar