I believe my cfs was triggered by a serious illness. i recovered from the illness, but cfs feels like i'm constantly sick, weak, achy. are my flare up symptoms from new infections? or is it my immune system reacting abnormally to everyday things?

It looks as if it is not a new infection causing the Chronic Fatigue Syndrome like you think, because it is a chronic relapsing disease. You may try graduated exercises and stretching on a daily bases to see if that is beneficial. It is sometimes mind over CFS.

Unfortunately, the symptoms of chronic fatigue syndrome can last a long time. Continued symptoms that you describe does not necessarily mean you have either a new infection or an abnormally reactive immune system. You should be under the care of a doctor so that your symptoms can be monitored and appropriate treatment rendered. Best of luck to you!