Unsteady when sitting still, right side.

I’ve been experiencing a swaying sensation while sitting at a dining table on a standard chair — specifically on my right side, as though something is subtly off with how I’m grounded, even when perfectly still. It’s not dizziness in the conventional sense — there’s no spinning, no blurring, and I’ve never fainted — but it mimics the unease of dizziness without actually being it. It makes me want to get up and leave rather than stay seated. The sensation is significantly better when sitting on a sofa. Standing still also triggers it, though walking feels manageable. It first began during pregnancy and has persisted since. I did have anxiety alongside this which has improved with gradual exposure work, and I was unable to stand or sit without feeling it but now its majorly when sitting but the swaying sensation itself hasn’t resolved. I’m looking to understand whether this is vestibular, musculoskeletal, or something else — and which specialist would be best placed to evaluate this.