I had a ct scan because i thought i had a seizure nothing showed up on the scan is it possible they missed a tumor? i have apathy, tired, weight loss

Possible: For tumor identification, a CT scan or an MRI with contrast should be done. Was your scan done with contrast? If it was with contrast and still negative, you should follow up with an EEG - if abnormal you should then get an MRI. With your symptoms, certain labs may provide information as well. Please be sure to get a referral for a neurologist for further workup.

Unlikely: Although precision of a CAT is less than MRI, unlikely that a "tumor" was missed. However, a better test for seizure issue is an electroencephalogram (EEG). You also describe some additional symptoms, which should be assessed by your doctor.