Hello @badi and welcome to Mayo Clinic Connect. It sounds as if your husband's journey with NETs has been a difficult one.

Have you considered consulting with a NETs specialist? General oncologists are not always well-versed in the treatment of NETs. Here is a listing of NET specialists, from the Carcinoid Cancer Foundation. If you are not able to have an in-person consultation, you might consider a virtual consultation.

--Find a Doctor
https://www.carcinoid.org/for-patients/treatment/find-a-doctor/
You were asking about help with diarrhea. While I've never had that problem, I have heard of a product called, Enterade, which others have used and claim that it helps. It is my understanding that it can only be purchased online. Here is information regarding this product, https://enterade.com/.

PRRT chemotherapy is the latest type of chemotherapy used for NETs. Here is some information about PRRT:

--PRRT Therapy
https://www.carcinoid.org/2018/07/26/peptide-receptor-radionuclide-therapy-prrt-updates-and-locations/
Has PRRT therapy been considered by his current medical team?