RH is nearly always the number1 cause of Bud rot.
There are sprays out there that will help to slow it down but an early harvest should be your priority.
As you have experienced this problem before i would look to try and find your problem within your grow room.
inadequate air circulation/exchange.
Plant spacing, causes micro-climates between leaves with seriously high RH.
General RH to high.
I suffered with the micro-climate issue on my last grow, chopped at 8weeks when they could have done 9 easily. Lost around 2oz but still bagged 12.33oz. For the last 7days before i chopped i used a forcing solution called GHE RIPEN. I now also own a dehunidifier.
J