I have never associated turmeric (curcumin) with feeling bad, other than the fact it can play havoc with indegestion if I try to take it on an empty stomach.
I love the stuff and take it regularly as a cancer preventive. I take Super Bio-Curcumin from Life Extension Foundation, which I get at a discounted price at iherb.com. It is much, much more absorbable than regular curcumin, which the body normally absorbs very poorly. If you take regular turmeric/curcumin you can help the absorption somewhat by taking it along with coconut milk or regular black pepper.
I personally take 400 to 800 mg regularly. For people who have agressive, difficult and/or late stage cancers we recommend up to 2500 to 3000 mg per day.