Mystery Digestive Problems

I had parasites up until I finally got rid of them last year. Since then, I have been experiencing bad digestive issues. I will spontaneously get bad stomach cramps, bloating and a lot of times diarrhea. These attacks last about 3 days. Even when these attacks aren't happening, I never go a day without a stomach ache. I have tried eliminating foods to the point where I only eat chicken, turkey, cauliflower, guacamole and eggs. I can't find a correlation between foods I am eating and the digestive issues. I take probiotics every day. I was diagnosed with candida and am taking medicine to address that, but I am not feeling any better. I wasn't sure if anyone else experienced these same symptoms and received a diagnosis. I have seen a bunch of doctors and nutritionist and still haven't been able to pin point a cause.

I had a colonoscopy but it was a couple of years ago right before the parasites were discovered. Nothing came up in the tests. I don't usually take anything for the cramping. Sometimes I take activated charcoal. Is a colonoscopy the only way to identify colitis?