I feel your pain! My office chair is a metal folding chair. It's so important for us to take care of our bodies. Have you considered an Epsom salt soak? I am not a doctor! But I've heard it can provide soothing relief to aches of the mushles.

I think I was onboarded to HR Corp® after this gif. It's exactly you, fitting even today at 61. You've come so far! Pretty soon you'll be a mega whale and I'll be the wrasse eating your barnacles when I can. Your back will be feeling better soon. ☺

PS When you're ready to purchase a new chair, you might consider purse.io to buy a chair from Amazon using BTC at a 15% discount. Sounds spammy, please forgive me for that part, but it's all true. If you haven't used purse yet, it may be worth a look.