There a number of different conditions that could cause the cloudy feeling you have. I am guessing it is the same as the "brain fog" that many other people describe. Brain fog, along with non-refreshing sleep are vague symptoms that don't always have an obvious cause.
Some possibilities are autoimmune disorders such as Sjogren's or MS or Celiac, as well as Fibromyalgia, Thyroid malfunction, and some infections, such as Lyme Disease. (I have Lyme and I had the same mental sluggishness and fatigue you describe for 6 months before other symptoms started.). Some nutritional deficiencies can also cause this feeling.
Your best bet is to go to your regular doctor first. S/He can do a number of blood tests to see what direction they point to. A CBC, a metabolic panel, levels of vitamins and minerals whose deficiency could cause fatigue, rheumatic factors, ANA, Lyme (although negatives don't exclude it), immune systen function, and others would give you more information and might point you towards a particular specialist, such as a rheumatologist or neurologist.
Good luck! And go see your doctor soon. The diagnostic process sometimes takes a while.
PLEASE SEE A NEUROLOGIST RIGHT AWAY for an MRI of your brain and some blood tests. It is normal to feel a little depressed when you just dont feel like yourself. Your problems are not normal for your age. You will have to go thru some testing to figure it out so be patient... Ive been thru the same thing so I know how you are feeling. Its frustrating. But get to the specialist doctor right away and figure out whats going on. Dont delay!
Yep you need a CT Scan or MRI ...just to be 100% sure everything is okay...there....