I have MS. I have/had a lot of the same issues, nervous system problems can look alike from the distance.
My MS was there all along (I ALWAYS had balance problems) but after a passed-out drunk drove head first into the front of my car my MS got triggered big time. My once pretty reliable memory disappeared, the only thing I could remember from one day to the next would be in the total disaster category. I ended up with compulsive note-taking at my job since I just could not remember from day to day. Then I read about Ginkgo Biloba, did some further research, went out and got some, and three days later I could remember MINOR stuff from the day before.
My memory is still bad, but at least I do have a working memory now. If you want to try the Ginkgo Biloba check with your doctor, of course.
My balance never got better. Riding horses was what got me going again, from having to use an electric wheelchair or a wheeled walker to being able to go over most types of ground with two canes at a decent rate of speed. I can even walk a short distance without my canes now. When my overused electric wheelchair gave up the ghost I did not have to replace it, and over a decade later I feel no need to replace it.
Though I still had horses back then I was not riding them, it was just too exhausting for me to get the horse groomed, the hooves touched up, get the horse tacked up and then mount, I was so totally exhausted.
I decided to get back into riding I had to find a hunt seat stable nearby me (car trips are exhausting) that would be willing to let me have a 30 minute private lesson on a school horse, with someone else catching, grooming and tacking up the horse. I told my riding teacher that I NEEDED her to be a position Nazi since I do not have a proprioceptive sense, to go along with my horrible balance, bad coordination, and tendency to get completely exhausted after any physical effort.
So for over a decade I have mostly been walking with some slow trotting. I have found that these sainted school horses like carrying me better if I look after their comfort, basic things like BOT saddle pad, BOT poll cap, BOT exercises sheet (their butt blanket) and now in the cold weather a BOT neck rug. That way, in the cold winds of winter, the horses do not feel like they have to run around like crazy just to get warm, they can just huddle under all the “clothes” I put on them. They like my Micklem bridles (I cut off the chin strap), they really like my titanium bits, and they like me riding Forward Seat and giving their head freedom even when we are on light contact (my hands belong to the horse’s mouth.)
My riding teacher uses me. I told her I would ride whichever horse she wanted me to work on. I have ended up on horses with some challenges, mainly from bad or no training, old age, arthritis, and at first I mostly end up telling horses that even though I am a WEAK rider with no balance they still have to obey me, just like they are expected to obey a small kid who is just beginning to ride.
For my balance problems I have found the most help from Rider Grips (RiderGrip.com), rubber disks that self-glue onto the saddle flaps, and silicon full seat breeches. With these giving me a reference point and preventing me from sliding around in the saddle I can keep in reasonable balance with the horse and not slide around the saddle.
I also use stability stirrup leathers (mine are the leather Millbrook ones), the Tech Venice Slope safety stirrups, the RS-tor riding aid, and a grab strap.
You may need help your first rides. The handicapped riding programs can help you there. One did help me but I needed to ride more (it is my physical therapy) and I got sick and tired of being led around, so I went in search of the hunt seat stable where I ride now with no one leading the horse around.
I can’t do much on horseback, but both the ladies who let me ride at their stables like what I do with their horses and how their horses usually improve for other riders.