Happened to me with grape flavored e-juice.
I chalked it up to my brain trying to trick me into smoking instead of
vaping. Trouble is it worked. Each puff from a vape caused me to want to smoke. I could go hours without wanting a cigarette but one puff from a vape device had that urge to smoke again in turbo-mode.
For those that are going to say "up your nic", the higher the dose the worse the urge to smoke. Cut back to 6 and things settled out.