I am one of the unfortunate thousands whose tweet got blocked by twitter due to suspicious content. The good thing was twitter provided a 'learn more' button at the end of the blocked message.
I clicked on it to find out a link given by Google that will investigate your site's content and declare whether it is malicious or not.
I tested the link that I tried to tweet and Google declared it clean.
Here is that useful link to test your website.
Replace 'example.com' with your site URL.
Share this useful information.