6 days for the lime is a little early for it to take full effect in the pelletized form.6.3 is ok,6.3-6.8 is optimum for soil. Ph is a major pain,i learned the same way you are right now and done the same things you did. You'll always remember to check your soil ph BEFORE you plant in it from now on,always easier to get perfect before the grow starts. As far as it only effecting one plant while the others are fine,theirs always one in the crowd thats weaker then the rest and that's where any trouble starts.