Some thoughts from my own continuing experience:
Second the thought of using the ball in places where it's not obviously hurting. I have a curve in my spine and am too swaybacked for my own good, and I've struggled for years with pain/tiredness in the left side of my sacrum. Turns out the source of the problem is the right side -- basically, the connection is too tight into the right hipbone, which is over-stretching the left side, so I "feel" the pain on the left, but the thing that gives me relief is when I work on the right side. Same thing front/back/btw -- the left hipbone is rotated a little forward, so again, overly tight in front is over-stretching the back. That ball is one of the cheapest and most effective tools out there; you just need to apply it to the right place.
Examine your WFH setup. If you were generally ok when you were working at the office, but have started to suffer since moving home, logic says that there is something different about your setup that is putting extra strain on your lower back. I had that exact issue, because I have a desk that allows me to stand or sit at the office, so sitting still for three solid months pushed my back over the edge. So I bought a thing that sits on my desktop that I can adjust between standing or sitting so that I can at least get a break in my position.
Do appropriate strength-building exercises, particularly focused on the core as a whole. Yes, yoga, for sure! But if your back pain is muscular and not disc-related, the problem may be in your posture and/or your core. Again in my case, because of the swayback thing, I lean forward too much, which means my back muscles just have to bear more of the brunt of the teeny day-to-day movements, like walking. That means both that my back muscles get tired out from working too much, and my other muscles atrophy, because they are not being used much. So getting the back some through stretching or massage or whatever is very helpful, but unless and until you really work on building up those other muscles so they can work like they need to, you're going to still have problems. Believe it or not, I started strongman training, partly because it was fun, but also because it seriously helps. By far the most helpful exercise is carrying -- or just standing with -- a heavy bar or yoke on your shoulders, because it forces you to stand up straight and activate all those postural muscles. Or walk around the room carrying a dumbbell over your head in one arm (straight arm) -- again, forces your posture and core into shape, and it's something I do regularly as a warmup just to remind those muscles to work. I'm also doing a lot of back squats and -- believe it or not -- deadlifts, because in order to do those properly, I must activate my glutes/hamstrings and my core (the weak muscles). Obviously, I work very hard on proper form, avoid specific exercises that set off the back,* and don't get stupid with pushing max weights when my form suffers (well, at least I try not to -- the stupid does sometimes take over).
If you want to see someone, I would recommend someone who works in sports medicine -- not an orthopedist, they're basically surgery or ibuprofen or "stop doing that,"** but someone like a sports-focused PT or masseuse or acupuncturist. I completely lucked into an acupuncturist who is less "traditional Chinese medicine" and more "what helps sports performance" -- she is an athlete herself, and she has a whole bunch of tools that she takes out to find and attack the source of the problem (by far the worst of these is the spoon you get in a Japanese restaurant to eat miso soup with -- OMFG it hurts, but there is seriously nothing better). She has been instrumental in helping me figure out what muscles are working and what muscles are messed up and in targeting the particular areas. She un-stuck my right shoulder within a few months (30-yr-old rotator cuff injury that I had been stupid and ignored when I hurt it in college because I wanted to finish the season, and did I mention I was stupid?), and I go to her religiously for my back. It is a long process; after all, I have more than 50 years of fucking it up. But I can't even begin to tell you how much better it is than it was 2-3 years ago. The fact that I can go out there and deadlift 225# with zero pain is a HUGE win.***
*For ex: our coach likes to do a couple of drills to work different aspects of the deadlift. The one where you pull the bar from a rack about 8" off the ground feels completely awesome; the one where you stand on a 45# plate and reach down extra far for the lift absolutely kills me. So I do the former and not the latter.
** My one attempt at a sports medicine ortho for knee pain ended when I was telling him that it was painful when I was doing back squats, and he looked at me with this look that said "WTF is a 50+-yr-old woman doing doing 200# back squats?" and just told me to stop doing them. I wanted someone who would help me figure out why my knee hurt and give me some things to do to make it better.
*** Fuck you, Mr. Sports Medicine Orthopedist.