Is there a condition that leaves your brain feeling foggy, fatigued, and blank?

For some reason I can't seem to have a nice long decent conversation with anybody. My brain goes blank a few minutes in and I end up not being able to think of anything to say. Not only that but my words and sentences are also usually very awkwardly structured and incoherent. I can never seem to come up with the right words at the right time or describe a situation or express myself clearly. I always end up stumbling on my words and thoughts. Please let me know what I am experiencing and if there is a cure for this. Thanks.