I still don't think vaping would be a primary cause for the sudden weight gain, but when in doubt it might be a good idea to try moderating all existing habits while waiting for the appointment and maybe start a new habit of going on regular walks. It helps fitness and metabolism (burning off calories and restoring muscle) and with stress and blood pressure too and you get some free endorfins as a bonus. There are also quick and simple HIIT interval training methods like interval squatting that can be effective in restoring fitness while taking only few minutes a day.
While waiting for the appointment you could familiarize yourself with potential causes such as
fluid retention, metabolic disorders or the connection between heart and dental health to see if anything rings a bell and just to be better informed when talking to your doctor.
You should also list any medications you have taken over the last year (probably comes up during the appointment) and check their potential side effects.
This can actually turn into a good opportunity for self-improvement and understanding.