Does a ct show all abnormalities such as a tumor, aneurysm or bleeding, ive had horrible headaches and dizziness and they said the ct is clear, they gave me some medication that helped but they havent stopped and im really worried. ?

No: A CT will provide information related to structural changes only. Functional changes would not be revealed by a CT scan. Headaches are many times hard to diagnose as they may reflect referred pain and a full ear, nose and throat exam with attention to C-spine would be required. Stick with one physician, ideally neurologist until workup completed.