S.O.
You're not alone. My son is 2 and I have felt unlike myself for a long time. I used to consider myself smart but not anymore. Maybe on a good day :) I don't know what it is. Most likely sleep deprivation for a long period of time? I am also a stay at home mom so I don't think I am quite as challenged as I used to be, mentally that is. I too have trouble spitting the right words out! I hope you find a solution, let us know if you do!
S.