I think I’m dumb

I don’t know if it’s fixable. My brain doesn’t work. Idk what to do. I say things that don’t make sense. I’m tired and I want rest but I feel stupid. I say illogical things and idk why. “You just have anxiety” or whatever doesn’t feel right. Why can’t I remember what I read? Why can’t I improve at anything I do? Why am I so slow?