You may just have to harvest its to big a plant to keep up with the bud worms if you saw 1 there are more that maybe did not even hatch yet   Deep in the buds there going to eat your plant from from the inside out the rot you see is from them eating 
With my amnesia haze every day I was checking her inside out finding little white eggs some rot I would pick it out and finally I found the little worm 🐛 now I know what the problem was 

save what you can!!!