If you do liver flushes, make sure you are doing adequate fiber and I would recommend activated charcoal for additional support. Cleansing the liver will put toxins into the intestinal tract for elimination. So probably you dumped toxins out of the liver and they just ended up recirculating thru out the body. So using stuff to "grab" the toxins will eliminate the recirculating.
I would suggest doing a longer term approach to Liver Cleansing using herbal approach with some liposomal glutathione (Readisorb) and some phosphatidyl chloline.
Liver congestion is always going to be a problem with any infectious problem like CFS. You may also consider tapping acupunture points (liver meridian)