If it were me I would just do up to a dropper full to a 2qt bag, after doing a couple of cleansing warm water enemas. But I have used garlic, acv, coffee and different herbal tinctures, so I have no fear. As far as male fern, that is one herb I have not tried, maybe someone else has experience with this herb in an enema.
As for why you feel worse at night, it's the opposite for me. I feel better as the day goes on, and it was that way for me in the beginning as well. It could be what you are eating during the day, general fatigue - on top of what parasites zap from you, or it could be die off from the herbal cleanse you are taking during the day building up into the evening.