do you have migraines? the vision problems sound a lot like migraines, if you're having headaches too, which are very treatable. I don't know about the other stuff. are you on meds? some meds can make you slow down mentally. nothing serious, just a kind of annoying side effect. also when extemely stressed you can have confusion. do you have panic attacks? I know with some people they feel like they could pass out or even have a heart attack when it's really just a panic attack. heck, sometimes just severe anxiety can cause most of these problems.
I'll be 100% honest with you. I doubt it's a brain tumor. There's a girl on another forum I'm on and she often worries about health issues, always fearing the worst. It's just another form of an anxiety disorder. I'm not saying you should ignore your symptoms though. If you're worried you should talk to a doctor about these symptoms. Try to relax and you may be surprised that some of these problems go away. If they persist or get worse you should definitely call a doc.
Bipolar, panic disorder, PTSD, PCOS, hashimoto's disease/hypothyroidism, acid reflux, and in the process of being diagnosed with either crohns, colitis, or even lupus...who knows really! the docs sure don't lol. Now possibly even celiacs disease!Lots of tests coming up so hopefully I'll know more soon. Too many meds to list!