I want to second the advice of smilineyesms305--especially the parts about vestibular therapy and vision therapy. (I think in the uk vision therapists are called "behavioral optometrists.") These are both really promising forms of therapy, if you can get them.

You can also try a weighted blanket for overstimulation and anxiety. It really helps me with both. There are several online sites that sell them; here is one:

http://www.sensacalm.com/weighted-blankets/

I think it's best if you can get in at least 20 minutes at a time with the weighted blanket, perhaps several times a day. Some people sleep with them, but I get more benefit from lying down with them during the day once I start to get overstimulated and/or anxious.