Your cognitive ability seemed better with alcohol in your system because that's what your system was used to. it can take some time even after withdrawals to get your brain used to being without the alcohol.

my ex was just explaining what the alcohol does in the brain. he is trying to quit, and is the worst alcoholic i've ever known.

avoid the alcohol if you can, and get stuff checked out by a doc. hope you're ok. my memory has gotten worse, i think it's age for me, idk.