I’ve been there a few times Seabear. Each time my meds have been tweaked, to good effect. The last bad flare was 12 years ago and stress related. I was just as you describe, every aspect of life restricted, constant debilitating pain and exhausted no matter how long I slept.
I managed because my husband took over and I lay around. I’d fall asleep about 2pm on the sofa and didn’t wake till 4 when I’d feel groggy and exhausted. I was reviewed and prescribed the next level of drugs, injectable biologics. It changed my life by modifying and controlling this aggressive disease.
If you’re already on them, maybe your rheumatologist will switch it
Meanwhile I think you’ll have to be advised by your body and rest but try and fit in short walks, fresh air, eat well and try not to feel wretched. Best x