You can purchase DE from several of the specialty online stores, but you'll pay a fortune for a minimal amount. I literally consumed pounds of the stuff to no avail. But perhaps you might have better luck with your issues.
You can get it in bulk for cheap cheap (compared to the specialty stores) from an online store called Agri-Growth International.
They also carry a herbal anti-parasitic capsule formula called 'Clear'. Some people rave about! It's expensive...but also did nothing for me either.