I am a progressive MSer and I have daily problems. I count all of my symptoms daily and track the long term pains to advise my neuro. I do not specify flare or other....I count them as my MS problems. I generally ignore those which bother me daily as they are part of my "normal" daily life. When a problem persists for more than a day, I note it for my neuro. My leg could be described as what you experienced, only mine cycles through and lasts for 2-6 months. I use a heating pad and this kills the pain for me. My neuro recommended cold compresses, but these did nothing. My GP gave me some demerol, but it did not work and I never had another dose. For me the heating pad literally "melts" away the pain. This does not work for every MSer, but I know my neuro passed my heating pad advise on to others and many of them got relief.
I have learned that if I use the heating pad early, I can "recover" more quickly than any other method At the slightest "hint" I will stop, rest, and heat.
Try some cold compresses first.