Hi Jean, welcome! Sorry you are having a rough go of things, but we've all been there and there's lots of advice/suggestions/support you can rely on on this site. That's good you're going to see the GI tomorrow; he will review your symptoms, but won't be able to tell you much just based on your symptoms. Diarrhea and cramping are two of the most vague symptoms out there and can be caused by a vast array of diseases/syndromes. So the first step is to get through the colonoscopy, which can rule out a lot.
It would be very helpful for your doctors if you keep a meticulous food diary. Write down how much you eat, what you eat, what time you eat, etc. every day for at least a couple of weeks; also keep a symptom diary. Sometimes it's hard to notice patterns, but keeping these diaries will be invaluable.
Keep us posted on how things go at the GI.