For intermittent pain, it's the spacticity/cramps which hit me worst in the muscles between the small bones of my feet. I also get nasty ones in the calf muscle whenever I try to straighten my leg all the way out.

For constant pain, it's a terrible nerve pain that I get in my left eye. I personally think it's due to demylination of that Optic Nerve, having had multiple episodes of ON in that eye. It came on with my last ON relapse 2 years ago, and hasn't left me yet.