How long do you keep flying? Tricky question. If you think that it is Aerotoxic Syndrome, of course it would be best confirm it as best you can with the most appropriate tests, and if it is, to stop flying to avoid further exposure, sort out your health, then decide whether to go back to bleed air aircraft or flying at all. In reality it isn’t that straightforward decision with family, mortgages, etc. Ultimately your health is number one, plus if you think that you’re no longer performing in the aircraft to a safe standard, of course you have a duty to stop.
This is a good document from the Aerotoxic Association and makes for a sensible discussion on the matter:
Practical Guidance: A few thoughts for the assistance of exposed pilots