Schimmel?

Yes, you are 100% correct. That is bud rot and it looks like you have cut out enough. My 2c is always cut a bit more than you think, because if you don't, it will creep back in and you lose more by trying to save more. When you cut, you want to do it in the morning on a dry day so the wound dries as fast as possible, because a wound that stays damp can easily get infected. Do not spray anything on your plants after week 3 of flower. Anything you try to fix with a spray will come back and bite you 10x harder as budrot. You will also want to keep a very close eye on this plant now and if you see any leaves in the buds dying and becoming droopy, pull on them and if they come off easily, there is more rot developing on the stem and in the bud.