I have taken antibiotics a gazillion times, all the latest and greatest (most toxic!) and at high doses because I have had chronic sinus problems and frequent sinus infections. However, I don't have CFS. I did, about
2 years ago, start experiencing fatigue and loss of stamina, but it turned out to be hypothyroidism. Now that I'm on thyroid meds I'm feeling good, my stamina has returned, and have a decent amount of energy ... although I'm still taking antibiotics as if they were vitamins.
So my question is, have you had your thyroid function tested?