I’m a programmer with MS. Like you, diagnosed about 15 years ago, but still doing pretty well. I feel like I’m starting to notice the gradual decline more and more, despite not having had a serious clinical relapse for about 10 years (some minor ones).

Things you can try: Changing your drugs - maybe going for something drastic like HSCT.

Being patient and not panicking - if you’re currently having flare ups your symptoms will appear worse than they really are while there’s acute inflammation happening. Don’t forget that. If the flare ups get under control you’ll should see some recovery and improvement.

Not giving up - keep pushing yourself as hard as you can, make sure you’re training whatever’s left of your central nervous capacity. There’s probably still some left. Keep trying to do as much as you can and you’ll get access to it.