That’s exactly what happened to me in 2022; had every imaginable test possible & last test they finally found it! Ended up with a small bowel obstruction & surgery 2 weeks later to remove it, pathology confirmed NETS. No follow up treatment except for lab work & CT scans that showed nothing until 2 years later when a PET scan showed it had metastasized everywhere. Referred to NETS Oncology Specialist/Surgeon who performed cytoreductive/debulking surgery. HUGE painful surgery! Three weeks later I started monthly Octreotide shots. Nine months later I currently only have one very small area in lower GI & have been referred for Lutathera/PRRT treatment. Definitely stay on the Drs & DEMAND a GA dotatate PET scan for anything suspicious as the CT didn’t find my Mets. I’ve done great, never felt bad (after healing from surgery) & live a normal life. Monthly injections are painful so I use lidocaine to numb the area prior to injection. I wish you well!