Memory problems, focus & concentration.

I have quit smoking in 4 months ago After that i got the after effects of quitting like and i gone through depression anxiety dizziness light headedness after over coming all that issues i was worried so much abt my health i started googling all this things which were happening to me after that i started getting memory issues like things doesn't going in my mind difficulty concentrating and focus not able to remember things which happen sometime before i have to pressurise myself to remember things and now while doing any task i am not able to think before i do anything and when i think abt something it feels for eg - i drive car but now when i think abt driving i cant able to think that strongly whether i will drive car first i was not like this this is happening from last 2 months and i have also done mri,xray all reports are normal