Re symptoms , going off this list from c o n d i t i o n s c h r o n i c f a t i g u e syndromebasicssymptomscon 20022009 I only haveFatigue Loss of memory or concentration a little , when I ' m tired Sore throat Enlarged lymph nodes in your neck or armpits Unexplained muscle pain Pain that moves from one joint to another without swelling or redness Headache of a new type , pattern or severity when I crash Unrefreshing sleep actually sleep and rest do help me Extreme exhaustion lasting more than 24 hours after physical or mental exercise if I have overdone it , but not if I pace myself correctlyMy doctor was pretty open about how little is understood about these types of illnesses . Apparently , though it ' s often assumed that the immune system is involved somehow , no one is really certain . It could be something else entirely .