I think there is another recent post about anxiety. I think you should go and see your GP if you feel that your anxiety is getting too much, I'm sure they can give you something or advice to help you feel calmer.
Sorry that you're struggling with this, but it's good that you're acknowledging it and are wanting to get help. Something that might help is CBT (cognitive behavoural therapy). I took part in a research project that involved doing an online course in it, and I found it really helpful. Although I don't particularly get anxiety, it is one of the things that CBT can help with, as it helps to re-train your thinkng and thought patterns.
It's something that your GP or MS nurse should be able to refer you for, so give them a call to try & find out about it.
Hope you get the help you need
The earlier thread on this was here: http://www.mssociety.org.uk/node/632372. Hope it helps.