Advice ?????

So I’ve had a very bad cavity since Easter , well before . And I got my cavity filled in maybe almost two months ago? And I have an appointment tmr at the dentist for a cleaning but I noticed now theirs the cavity on the same tooth growing at the Bottom . Will they have to take my tooth out? Since they have already filled it in? And if they do have to take it out, will it hurt. Just asking so I know what to expect ( I have anxiety )