These symptoms could be caused by all sorts of things, and since they've been going on for more than a month without getting better, I would definitely recommend that you go to see your primary care doctor
. Your doctor will be able to perform a more detailed examination and ask questions to help get to the bottom of this.
I'm glad to hear that you are not using any alcohol or street drugs, as that was definitely my first thought when I read the question! Other than those common causes, it is possible to have this kind of sensation induced simply by extreme stress or fatigue, so the first thing your doctor will want to do is investigate your sleeping, work, and social habits to see if there is anything obvious.
If not, it may be necessary to consider other causes. For example, a problem with the thyroid gland could cause many of these symptoms of memory problem and "mental slowness". Similarly, a true sleep disorder, such as sleep apnea
, might cause the symptoms, particularly if there is a history of snoring
or gasping during sleep. Finally, in some cases, these "spacing out" episodes might be signs of a subtle seizure disorder. Please speak with your doctor.