Thank you all for your suggestions and support. Kefir is helping!
Update: after nearly 9 months on the 80mg Tagrisso, in addition to the diarrhea I developed a full body rash (very itchy) and my fingernails became quite brittle and seemed to stop growing. I shared these new symptoms with my oncologist and he agreed to drop the dosage to 40mg. Thankful - and hopeful that this will ease the side effects.

I was diagnosed Stage 1B adenocarcinoma in January 2025 and had my partial lobectomy (with a robot assist!) in February 2025. As many have said, this is a journey ....