If your MCL merely aches in the same way that your muscles would after hard exercise then they're probably right. If it hurts though it's probably the body's way of telling you to stop doing what's causing it.

I'm now seeing a sports therapist that has worked with Sheff Utd football club & Sheff Eagles rugby club so she's seen this type of injury plenty of times.

My own MCL gets set back when I do any running, either treadmill or road. She's has told me not to do any running at all until it's 100% better. I am doing all of the things that you are doing and I do feel that I'm progressing but you're right it is slow and with patience it will get better so long as you don't aggravate it. That has been my problem, lack of patience and trying to get back to normal activities too quickly.

Good luck, Mark