This is not ocd, but it's disturbing thoughts, should I do a brain scan?

Do you think a brain scan can be a way to understand psychological behaviors? I feel like there's something in my brain that disturbs me all the time. My thoughts are going around and around. Especially there's this disturbing field around me, which is there 24/7. At first I thought it was ocd, but after talking to a psycologist we came to the conclution that it wasn't ocd. I've tried to avoid these thoughts, but this disturbing feeling around me just doesn't go away. I start to suspect there must be something with my brain. It feels like a part of my brain is overactive, heavy and just generally 'disturbing.' Anyone know what this could be? what kind of medication is there for diseases like this? do you think I should do a brain scan? Worth to mention is that I've always been suffering from anxiety. When I was a child I had a hard time sleeping at night, and I suspect my 'alarm system' has been pretty vulnerable ever since. Howevrer, id describe this feeling as distubing, sort of when you have an eyelash in your eye, or allergy on your body. It itches and you just want it to **** off. And I feel it's all going on in my brain. ALso, if anyone professional might read this, maybe you could tell a little about what this could be? thanks