It is common for PD symptoms to first "bloom" after an unusually large stress, both physical and psychic. In my own case it was a bout with the flu. I had had a tremor for eight years with little worsening until then. Currently I am dealing with huge mental stresses as a result of the real estate crash and I can feel a need to be very wary-a sense of fragility. I think the answer is clearly yes, we are subject to periodic drops and I do think that stressors are the trigger.
As to what actually happened in Ron's situation, I can only speculate. The infected tooth resulted in at least three changes in the chemical soup beyond the leaking BBB. 1)Exotoxins from the living bacteria, 2)Endotoxins from dying bacteria - was there an antibiotic? and 3)Increased pro-inflammatory cytokines from the immune system's microglia. The first two have presumably been taken care of with the infection but number 3 can be a bear. Liu, Hong, and other researchers at the NIH found that in a rat a single exposure could trigger a response like number 3 that lasted for months.
What to do? I can only tell you what I would do for legal reasons. First, I would look for things that attenuate the microglial response. Medline suggests that likely ones include resveratrol or red wine which should be easy to obtain; others
include blueberry extracts, minocycline, silymarin, etc. Also, our old friends curcumin and dextromethorphan.

I would also keep up my own ginseng and gingko for general toning of my systems.
-Rick