I am just now finishing my master's degree. My tips are to start slowly with classes that are easier while you are learning to pace yourself. See the student disability center for help with things that you need. Since we are all different, you would need help with different things than I do. See your doctor for medicines to help you sleep. I am taking zanaflex at night and that helps me not tense up while sleeping so I wake up less sore. Do not take classes back to back, but make sure you have spaces between them so you can move around. It is difficult to sit all day and it is difficult to walk around or stand all day - you need to do both. Tell your instructors about the fibro and the trouble it causes you. Your professor will understand better if you have to get up and stand in the back of the class for a few minutes. Do light stretching to keep your body moving. Study with other students. This helps you retain things better (whether or not you have fibro). See your professor during office hours for help with things you do not understand.
I agree that getting out of bed is a chore - but you should feel better once you do get out of bed and start moving around. You might not feel great, but moving around helps loosen up the muscles so they hurt less. It takes me from 30 minutes to an hour to work out the stiffness. If you can have a morning and evening routine to help you wake up and sleep, that will help, too. Also, if at all possible, keep as regular schedule as you can. With school, that is sometimes nearly impossible, but do your best.
Oh! and if you get fog and cannot think, do not push yourself. That makes it worse. Take a break. You might be able to get more time to take tests if this is a problem for you. I am pretty good with statistical analyses, but sometimes I look at it and it might as well be advance physics. I don't stress, just stop and go back to it later.
Hope this helps!! Good luck!