What is wrong with my brain and how do I get it to work like it should be working?

I have been told my brain is not fast enough and I feel like there is a lot of fog just sitting on my brain,last year I took an over dose of my medicine and I felt like someone was vacing all of the air out of my brain where it is getting smaller and smaller,I don't even use big words and I don't know any,I feel like I am dumb and can't do anything,I watch Jeopardy and I don't even know the answers,I need some advice on how I can reset my brain?