zoloft making me feel brain dead really scared

i was on paxil for a long time over 10 years and i crashed one night where i couldn't focus or concentrate on anything

my doctor switched me to zoloft and the symptoms are even worse now that i started zoloft i can't focus or concentrate in just zoned out constantly im so scared i tried to stop taking the zoloft and felt more clear but i keep getting withdrawals and had to reinstate i don't know what to do