I hear what you're going through. I'm 10 weeks in to my second pregnancy and I felt the exact same way a couple weeks ago. Luckily for me, it was just horrible bloat and its gone now -- thank god -- I was so upset when i went to uy new jeans in a size larger, -- and they didn't fit. - I refused to go up 2 sizes!
I'm doing better now, my clothes are fitting about the way they had been. Hang in there -- Hope your MS lets up soon!