Well, obviously your dirt isn't doing it all for you. It appears to me to be overwatered and the soil is too rich to allow for proper drainage. If it were mine I'd get myself a bottle of SuperThrive and transplant into the next size bigger pot using same soil but with a lot of perlite added to allow water to drain. It also appears you have been feeding it quite a bit so I'd cut back on that to none until the new growth shows improvement and no water after the transplant into fresh soil w/perlite until the soil has dried out (be generous with the SuperThrive mix immediately after the transplant but allow it to dry afterwards). Those damaged leaves will not recover and will eventually finish yellowing and fall off so don't worry about it when it happens. Just cut back on the loving and follow "The Book" and you should be fine.

And I should put this in my sig sometime...Check Your PH! Not just you but everyone who's serious about growing.