Hi, Thanks for writing in. A benign carcinoid tumor is a tumor which might cause release of neurochemicals which increase blood pressure and cause headache. It is possible that the benign tumor might have secreted certain chemicals which are directly related to causing headaches. Such tumor cells might be present elsewhere and they might continue to release the chemicals. I am not sure if you have been detected as multiple endocrine neoplasia which is also called MEN syndrome. In this condition there might be benign tumors in several places which might cause release of chemicals even after the removal of the stomach tumor. This requires detailed assessment regarding possibility of other similar tumors. Please discuss with your doctor and get complete evaluation done for it. Please do not worry.