Toxins being removed from the body (from many methods including parasite killing herbs) flow over the myelin sheath that covers the brain. This, in turn, irritates the Central Nervous System. When the CNS gets irritated - many problems occur such as: brain fog, anxiety, mood swings, Depression and so forth.
When you were taking your herbal formula - the herbs were helping to rid the toxins and you were able to get relief. This removal of toxins is also why many people diagnosed as "depressed" can get off Depression meds after a good parasite cleanse. The parasites that CAUSE the toxins are removed - and the CNS is no longer assulted.
Right now the best thing for you to do is try try and lower your toxin load. A Liver Flush will help dump out the load of toxins filtering through your liver. A good "detox" herbal formula should help too.