The down-turned ends of the leaflets on the yellowing fan leaves, along with the purple coloration lead me to suspect a phosphorus deficiency, and perhaps with nitrogen too. It could be a watering/drainage issue with that plant rather than an actual shortage of these nutrients. Under low oxygen conditions, you might be getting denitrification to an extent as a contributing factor as well.
I'd do a simple soil probe to check the condition of your soil deep in your pot. Just break off a wooden BBQ skewer or similar thing so that it has a very rough end with splinters sticking out and whatnot, but keep it long enough to reach the bottom of your pot. Stick it all the way down (rough side first), lift it up and give it a good smell with the rough part right under your nose. Does it smell like sweet soil, or does it smell like a sewer or barn? If the later, then we've found the problem.
If everything is good with drainage and watering, then it could very well be a lack of P and perhaps N. Things like alfalfa pellets break down quickly, but not fast enough to provide any benefit in the time you have left. If you can get a hold of it, I'd suggest a top dress of animal manure - chicken or hen manure pellets would be ideal and provide calcium too, but really any good strong manure will do as a source for at least some available P. Perhaps though the "Grow" stuff may help in time, but I have no idea of its potential NPK levels or how much readily available nutrients it might contain.
Hopefully you caught the hermie on time without too much pollen being released and blown around in there. Other than chop the offending plant if you feel you can't keep up with picking off all the sacks, there's nothing much you can do now except stay vigilant. There will likely be some seeds in your future - hopefully not too many.
