I agree with the PPs about getting a dev ped evaluation and contacting the school to start the screening/evaluation/IEP process. My DS has anxiety and having the accomodations in the IEP has made a significant difference for him - especially on the days when the anxiety causes him to act out.
You might consider looking into an NIH study on anxiety
http://www.clinicaltrials.gov/show/NCT00024635 . One of the researchers has presented at the FCPS Special Education Conference
http://www.fcps.edu/cco/prc/resources/events/index.shtml the last couple of years. I go each time because it's really interesting
http://www.fcps.edu/cco/prc/resources/events/documents/Fairfax10_11_2012.pdf After her first presentation, I contact NIH to see if my DS qualified for the study (we also had a friend who particiapted). DS did and enrolled in it. They did a lot of testing and gave me a lot of good information about what was going on with him and the severity of his anxiety. He's not as debilitated as some but it was definitely affecting his choices, his behavior at school and our relationship with him. For him, CBT wasn't sufficient. He's a little young to fully benefit from it so we decided to start him on a low dose of generic Prozac. The difference was amazing. The medication allowed him to better control his brain rather than his brain controlling him. He didn't have to spend so much energy on his anxiety and did so much better all around. He was on the mediation for about 9 months and then thought he would be okay without it. So, we tritrated him off it. He still has anxiety but no where near what it was. If it gets bad again, we'll start it again.
Good luck.