OK, man...like a previous poster said, sounds like you've got a salt lock situation, or a soil-too-hot situation. I've heard that the "hot" soil thing can be taken literally, too...some kinds can compost, and literally burn your roots. Idunno about your brand of dirt, never used it...
I have sometimes used the FF bloom additives (Open Sesame, Cha Ching, etc), and every time, my plants loved em. I do not think they suck. However, I think they are quite concentrated, and I KNOW they are very salty. Meaning: I dilute the manufacturer's recommended dosage somewhat (by at least 20%, more if they're in early flowering.) It also means that when using FF products, I have to flush more often than I would otherwise, because of the epic salt buildup. It's like the great salt flats; I could start a side business as a salt miner. It's SALTy, I tell ya!
So my questions to you are: how long was it since you last flushed when you started to see symptoms? Did you use as much of it as they advise? Is it possible that, as some other posters have suggested, you are seeing a reaction to having fed soil that already had food in it, earlier in flowering?
As already suggested, I'd say test your runoff and adjust (dilute) your nutrient solution accordingly.