Secretary of State Hillary Clinton was hospitalized Sunday after doctors discovered a blood clot during a follow-up exam related to a concussion she suffered this month, her spokesman said....Clinton, 65, was suffering from a stomach virus earlier this month when she fainted due to dehydration, causing the concussion.

The Official Statement from the US Department of State:

In the course of a follow-up exam today, Secretary Clinton's doctors discovered a blood clot had formed, stemming from the concussion she sustained several weeks ago. She is being treated with anti-coagulants and is at NewYork-Presbyterian Hospital so that they can monitor the medication over the next 48 hours.

Her doctors will continue to assess her condition, including other issues associated with her concussion. They will determine if any further action is required.