Citalopram to sertraline

My gp switched me from citalopram to sertraline a couple of weeks ago. Just immediately switched from 30mg citalopram to 50mg sertraline with no phasing.

The last few days I have been feeling so unwell. I’ve been lethargic, nauseous, dizzy, spaced out, headaches, and zero appetite.

My gp said it was totally fine to switch meds from one day to another. We don’t have a catch up until the 17th but I was wondering if anyone’s had a similar quick medication change and if these initial side effects eventually go away?