Gastro issues on 16:8

Hey everyone. I've been doing a 16:8 fasting schedule for probably a month now. I've naturally been a ~12 hour faster for a long time. I'm just not typically a breakfast eater.

Recently, I've noticed that I have a lot of upper abdominal discomfort at the 16 hour mark. I usually break my fast with low-fat, unsweetened plain Greek yogurt, walnuts, chia seeds, raspberries, blueberries, and strawberries. But this week, it began to make me absolutely nauseous. And..urgent diarrhea. I'm not sure what's happening?

Today I tried breaking my fast with a handful of walnuts. A half hour later a banana, and then about 40 minutes later two slices of sprouted whole grain toast with avocado. My stomach isn't AS BAD as it was earlier but still pretty uncomfortable.

My typical diet is Mediterranean. Lots of Greek salad, roasted vegetables, beans, chicken, salmon, and canned mackerel.