Triggers: Pyrethrins and Piperonyl Butoxide???

It's summer down here so the flies are buzzing about and the first thing you want to do is get rid of them.

Last summer I bought one of those automatic spray dispensers and that loosely coincided with the return of my headaches as full blown transformed migraines. The only problem was that once we stopped using them the migraines stuck about so I didn't make the connection.

http://www.raidautomatic.com.au/faq.html#10 : 9g/kg PYRETHRINS, 45 g/kg PIPERONYL BUTOXIDE

Winter came and I had a pretty easy time of it (more like daily tension headache than daily migraine) and then I was training full on for a big cycle event and I've since found I had some postural problems that may have triggered a return to the nasty migraines. However around the same time I also chucked another can of spray in the automatic dispenser.

Once the event was over and the can ran out and life went back to normal with a great physio helping me with the postural problems. I got back from camping and put another can up. Within 48 hours I was lying in bed in too much pain to even find my imigran. Turned it off and I'm back on my feet.

A bit of googling and all I can find is that there's a herb called feverfew which has natural pyrethrins and it's a migraine TREATMENT!

How can something that is a treatment also be a trigger?
Or is this a red herring?

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:)