Stage 4 Carcinoid tumor

To make a very long story short. Hubby was diagnosed in Oct 2022 with a carcinoid tumor. Dr removed a mass from the small intestine. He had a Pet Scan in November 2022 and the results were not good.
Stage 4 - Areas affected
Abdomen, Large scattered mesenteric lesions are noted
Mass lesion noted in the tail of the pancreas
Musculoskeletal System - Multiple dotatate avid skeletal lesions are noted = Starnum, left 4th rib, right acetabulum, Body of C3, C6 and T3
Head and Neck - SUV - 20.57 measuring 1.34cm x 1.13cm
Thorax - donate avid mass lesions are noted in close relation to the heart and also the right bilar, left hilar, and descending aorta medically
Conclusion of the PET/CT - Extensive dotatate avid lesions are noted in the tail of the pancreas, small bowel, mesentery, heart, mediastinum and atasseous sites.
To put in language that I understood from the Oncologist, bone cancer areas affected his neck, left ear, hips, chest and legs (bone).
He received an injection (I still don't know what injection it is) as Dr just explained that it is to slow the growth of cancer.
He had 4 injections so far one per month.

My concern is that hubby is getting weaker by the day in and out of the hospital with diaree. Last two weeks refuse to go back to hospital, He is losing weight and stamina. Can't even move without any assistance.

Is there a different treatment than the injection and what are the best medicines for diaree, I have tried everything change of diet, only liquids at one stage, and drinking supplements, but nothing seems to stay inside his body.

I would really appreciate any advice or suggestion. Thank you so much