Not sure if you've already found a cure for your back pain, but maybe my answer might help someone here.
A few years ago, I was short on cash and ended up buying a fake mattress. My previous mattress was no longer supportive and I therefore needed a replacement before I started developing back pain. But my biggest problem was oversleeping because the mattress was not comfortable at all. The new mattress ended up being worse than my old one. After days after sleeping on it, a dip had already formed. I regret purchasing it because I ended up developing back pain.
The good news is that my back pain didn't reach to a point that I would lose my mobility- but it did prevent me from enjoying myself or even having a good night's sleep. I've since bought a more supportive, high quality mattress but I have surely learnt the hard way.
But one thing I've learnt is that you can get back pain very easily if you don't learn how to properly protect your back. I noticed you learnt about long meditation sessions causing back pain. I've meditated a few times and I can assure you that there is a risk of developing back pain. That's why I bought a meditation chair with good back support. Of course, exercising regularly and performing certain yoga postures can help, but its important to use a meditaiton chair, rather than just using a mat.
One thing I know is that you should never compromise on your back health. I am witness that back pain can be disastrous and devastating. Another thing I regularly use to protect my back when perfoming chores is a
back support belt. I use it when lifting heavy things, when lifting weights, or basically when I need some good support for my back.