https://www.amazon.com/dp/B01ACH9FPG?psc=1
A good back support cushion will make any chair a good chair and as far as your back goes $2 chair or $2000 dolla chair means fuck all.
I've had lower back surgery and have made good coin online for 20 years, so I have no hesitation at throwing any money at a chair.. if it works.
And they all suck, I tried most as an instant cure in the past.
Don't sit in chairs that don't have lower back support, restaurants are notorious for this, tell them to get fucked, why they are getting told.. and leave.
And invest in a back support cushion, they work!