Can you use amantadine for fatique (ms)?

Yes. I have used it for many years with many patients suffering not just from MS, but other CNS and even chronic inflamatory illnesses (RA / SLE) with any slowed processing. May also improve executive functioning in some individuals. Be aware of rare corneal edema cases.
Absolutely. Amantadine is always worth a trial. It is inexpensive and can be beneficial in some MS patients. Should it fail to benefit the patient, other options such as Modafinil and Armodafinil may be offered.
Yes. Several approaches for control of fatigue include ritalin, (methylphenidate) modafanil, Nuvigil, Cylert, and of course amantadine. The latter is, in my experience, not quite as potent, and can cause livedo reticularis is some folks, but can serve as a subtle supportive agent in mild chronic fatigue.