My memory has been dull the past year and it has been getting worse and worse. Try not to overanalyze it. Anxiety and stress can wreak havoc, and also a number of other harmless things can cause memory issues, spacey feelings, or another cognitive symptom.
From what I understand, CJD is a rapidly progressing disease that quickly causes unmistakable symptoms that are usually not observable by the person who has the disease. Most dementia forms are like that.