Hi! there are those better qualified to answer your question than me. but if I were you
i'd still take anti parasite herbs- and I'd also go to a Holistic Nutritionist at the same time.
Also- I would start taking very strong probiotics, because it sounds that the drug they gave you also destroyed the good bacteria along with the bad in your intestines.
You need lots of good bacteria in your digestive tract to prevent reinfection of Giardia. Start taking Probiotics immediately! Yogurt is good-but you need LOTS of yogurt to have an effect-- Get Kefir also, and also get some probiotic capsules.
You need to continue taking probiotics- even after symptoms diminish. The drugs gave the giardiasis a big blow- but without enough good bacteria, they could establish themselves again in you.
I WISHHHH DOCTORS WOULD PLEEEEASE PERSCRIBE A GOOD PROBIOTIC TO A PATIENT WHEN GIVING THEM STRONG Antibiotics OR MEDICATION! yeeesh! this is my big beef, as I had a similar experience as you- with only being medicated for a bad flu. I had huge intestinal issues after that- and I was never warned. Luckily I went back to the doctors confused as to what was happening. The nurse said, "ohh, i guess you'll need a probiotic, your flora and fauna need to be replenished". I was like, "What is a probiotic and what is flora and fauna--flowers and fish..duh"
Now if they had written me up a prescription for a probiotic, I would have taken it immediately after finishing my bottle of Antibiotics - instead of being confused and miserable for 3 weeks afterwards!
You can find probiotics over the counter in capsule form- in many drugstores as well as healthfood stores.