I would definitely go! Don't let MS keep you from living your life. Worse case scenario, you have to fly back earlier than you thought, but even if you had a relapse while traveling...maybe you just lay low in the hotel after seeing the doctor. Go, go go!
Regarding travel insurance, I'm in the market too and I found that the World Wide Health International Plan from Travel Guard covers pre-existing conditions, including MS, as long as you're under 70. They said if I had an attack and needed treatment while traveling, it would be covered. I have yet to go through the 9 page terms and conditions document (doing that tonight!) but the representative said my MS is no problemo. Kinda tempting just to travel and keep that instead of my COBRA insurance - it's way cheaper too