I am a physical therapist but not a physician. I have treated a few AS patients. Please, do not let a chiropractor manipulate your spine. There are specific exercises for AS and ones that should be avoided. One of my patients benefited by swimming. AS for your classes, perhaps if you explained your situation to your teacher, they can make some type of accommadation for you. If it is more comfortable standing, then maybe you could stand for class and take notes on a lector stand. Good Luck and please beware of the chiropractor. Also, do not be afraid to use meds to make you more comfortable.