Hi, like Hvergerthi said, these sites are there to sell stuff, and they will exagerate the dangers and play on peoples fears. I will look around and see if I can find any that are credible :)
If you've had the Amalgam fillings for a long time, most of the vapours would have leached out years ago, and swallowing something that has been in your mouth for years is not going to harm you, particularly as you have got it out with the enema anyway.
If I swallowed something nasty, I would probably feel pretty awful, more because of the thought of swallowing it, than any real symptoms.
Please be at peace, you have done all the right things :)