Sounds like user error to me. Hopefully this is a dumb question, but you were sure to use Pure Food Grade only?
I have been taking it daily for almost 3 weeks now. I started with 1/2 tsp and worked up to 2 tbsp. daily (morning and night). I now am on day 5 of my juice/water fasting (trying for 30 days total) so I have slowed down on the DE some just as a precaution. It has helped me a ton with expelling critters! I also put it in my cat's food (started with 1/4 tsp in her moist food at night, now I give her 1/2 tsp only once a day).
My cat was really sick when she was a kitten. She had a severe URI and almost did not make it. She was 1 pound 3 ounces and would not eat. Luckily, the vet was able to save her. Now she is normal weight and healthy, but she always has respiratory issues, walking around sounding like she is stuffed up and having to sniffle to breath. 2 weeks on the DE and her sniffles are gone! She does still has running/watery eyes.
That being said, everyone's experience is different and I think CZ is about sharing experiences of our own healing journeys to help others during theirs and finding support, whether those experience are positive or negative. So if you had the negative experience, then okay.