oh wow, your story sounds so similar to mine. I was diagnosed last Spring and had the same tests run, slurring speech, trouble finding words, numbness tingling and fatigue. I also bought a new mattress a year ago which did nothing to help.
Try not to worry too much, I know it's hard to believe, but symptoms can improve. It seems like stress is the biggest cause of flares (at least for me it is) so try to avoid stress. I'm taking b12, vitD3, msm supplements and those help. I've also read about creatine helping and also D-Ribose but I need to research more before buying. Magnesium is another option but I've had my levels tested and they're always in the high normal range so personally don't take them.
Dietary changes are really helpful. I'm on a mostly plant based diet and make all meals from scratch, morning smoothies with fruits, veggies and sometimes protein like peanut or almond butter give me energy and help with the stiffness.
Medical marijuana helps too, I take a 50% cbd 50% thc liquid tincture under the tongue. It's a great option if legal where you live.
