。
You don't need to worry about what that fortune-teller said yesterday.
Literal
Yesterday [attributive-の] fortune-teller [attributive-の] divination [dismissive-なんか] worry-about [thing-こと] not-exist-[assertive-よ].
~なんか is the dismissive particle, downplaying the fortune-teller's divination. 気にする ('to worry about, to mind') with 気にすることない ('there's no need to worry') is a common reassurance formula. 易者 ('fortune-teller, diviner') is a slightly old-fashioned word for one who practices 易 (I Ching / divination). 占い ('fortune-telling, divination') is the general word for various forms of prediction.