There are several different possibilities here, and I can make some general recommendations about different types of doctors that should be involved in helping you figure this out if they are not already.
First, the fact that you have had a CT scan is excellent and reassuring, because it rules out many of the more serious causes of your symptoms, such as a large tumor in the brain. However, a CT scan is not the most definitive imaging study of the brain and so, if there are still questions, an MRI of the brain might not be a bad thing to consider.
It will also be important to have a full eye examination by an eye doctor
, if you have not done this already, as several diseases in the eye, such as a tear or hole in the retina or a buildup of pressure inside the eye, could cause symptoms like flashing lights.
Also, consulting with a neurologist
would be a good idea, especially if all of the brain imaging and the eye examination are unrevealing. The neurologist will be able to consider and rule out the various neurological conditions, such as migraine, that could be contributing to your various symptoms.