I’m sorry to hear this, but you’re lucky it was spotted when it was, as I think it’s actually much more pressing than MS advice - however much you’d been looking forward to the latter.
I’m appalled your doctor didn’t spot it, and it was recognized instead by a neuro. Not really their field, but full marks to him for being on-the-ball.
Reduced mobility from any cause is a risk factor for DVT, so yes, it might be indirectly connected to the MS, but isn’t really considered part of it - some people are prone to it even if they’re not ill with anything else - family history plays a part.
With luck, the thinners will disperse it naturally - however, surgery is an option if they fail.
I haven’t had one personally, but it is in the family - hence my awareness. My grandad had several, and my dad had one near the end of his life, when he was incapacitated by an unrelated illness.
It is potentially serious, but treatable - as you have discovered. I would not worry about the MS for now, if that doesn’t sound like stupid advice, as that is a chronic thing, not a medical emergency. You can always get another appointment scheduled for the MS advice you missed out on. Yes, it is annoying, but I think that is the least of your worries for the moment.
I don’t know if you may have to stay on thinners for life. It is possible - especially if disability prevents you from doing more to improve circulation.
I assume you are under medical supervision to ensure the thinners are working?
Longer term, I’m sure you will be given lifestyle advice and/or medication, to reduce the chances of it happening again. If you are aware there is a tendency, there are precautions you will be advised about.