It is possible you could have pinched a nerve when you fell, or it could be a nerve issue from ms. I've been having major issues with nerves in my left hand following a car accident. When it gets to tingling too much I find applying an ice pack and either using one of my splints or a simple ace wrap for a few hours calms the sensation at least... Too bad it doesn't fix the strength and mobility issue as well.

But pinched nerves can respond to the age old RICE, rest, ice, compress and elevate. Try it for a few days, if no improvement or signs of worsening then heading back to the doctor might be your next best bet.