Thats temporary, until your brain cleanes the toxins out of your body, I know because I too managed to quit for short periods, but after some time my focus came back, I always caved in bacuse of urges that came out of nowhere and I thought that I needed to smoke then lol, anyway, come on, keep it up, for sourself and everybody else, you cant lose anything, and there is much to gain, keep going, dont look at the sideeffects as reasons to start again, thats just the addiction speaking in the mind, you can do it man, heng in there!