Gretchen is right, the autoimmune family likes to stick together. It is great that you're doctor is taking you seriously, that's the first step. Your symptoms could be from MS or any number of other things. From the symptoms you have listed I would even consider fibromyalgia, which tends to hang out with the auto-immunes. I hope you figure out what is going on soon so that you can get some treatment.
It sounds like you find great joy in your family, don't lose that. It's easy to get discouraged when your body is falling apart, but even on a really bad day, you can still hold your kids close to you and enjoy being a mother.
Be joyful in hope, patient in affliction, faithful in prayer (Romans 12:12).