Double vision can be not just an eye issue, but an eye muscle issue. For instance, some neuro-muscular or some endocrine diseases can effect the eye muscles from fatigue, not a tumor.
Dizzy can be vertigo, and ear issue, etc etc. so it is very non-specific as well.
It is very unlikely to be a tumor - have you been to a GP and had an exam? What about an ENT? If the GP was suspicious about a tumor, he could have sent you for a CT right away.
Hi and sorry you have this problem. You symtoms sound almost exactly what I have as well. I have a retinal migraine which can cause all these symptoms, including throwing up. But it is good you are going to get it checked out because you never had it before. I have had a migraine variant with or without headache for years. The visuals only started recently. I am also going to an opthamologist to confirm I don't have any problem with my eyes. Let me know what they tell you. I doubt your symptoms are brain tumor related, but if they want to get a CT scan that is fine to rule out everything. They put me on a med that is supposed to lessen the number of visual disturbances and migraines too. I hope it works. Please message me after you see the neurologist and of course write back here if you have any questions that I can help you with.