First of all, I'm sorry about your challenges, but it sounded like you have a positive attitude which is so essential.
But a statement you made caught my attention. PRRT (which I have had) is not a monthly injection. It's a targeted, infusion treatment done every 8 weeks following a specialized PET CT (Lu-177 Lutathera) which identifies exactly where the tumors are. Sounds like your doctor wants to start you on monthly injections of Octreotide (Sandostatin) which are given every 28 days. It's frequently the first line of treatment. It should help the diarrhea, flushing, etc.
Hoping for the best outcome for you.