Vaping can affect some people regardless of nic levels.
A young lady I know was vaping 0mg, 50/50, got a bit light headed for a few days at first. Her stick mod wasn't restrictive enough, airflow wise, so maybe she was just getting a head rush?
I gave her a MTL tank, restricted the airflow and she was fine.
MTL is mouth to lung by the way, sorry if I sound patronising, not intended.
A pod system with airflow adjustment would be a cheap enough starting point.
YouTube is a great place to start looking, and the other peeps on here are a huge reference library.
Good luck, oh, & manners, WELCOME!!!