Per CBS Sports:
Coach Pat Shurmur said after Friday's practice that Pinkston is being treated for the condition, but provided no further specifics about Pinkston, a second-year guard from Pittsburgh.
Several of his teammates visited Pinkston on Thursday night, and Pro Bowl tackle Joe Thomas said "it's a little bit scary" to see a teammate who is ill. Shurmur would not say where Pinkston's blood clot is located and he does not know how long the 25-year-old will be sidelined.
Pinkston started last week against Cincinnati but became ill and was replaced by John Greco, who played the entire second half. Greco will start Sunday against Indianapolis.
Even though some might claim that Greco played better last week than Pinkston has all season - and at the very least there's not much drop off - it would be truly boorish of us not to wish Pinkston a speedy recovery.