The Ephemerides speaks of it in front of the hypochondrium.

Paullini observed a sailor of thirty, who, falling speechless and faint during a storm on the deck of his ship, sweated a red perspiration from his entire body and which stained his clothes.

He also mentions bloody sweat following coitus.

Aristotle speaks of bloody sweat, and Pellison describes a scar which periodically opened and sweated blood.

There were many cases like this, the scars being usually in the location of Christ's wounds.
De Thou mentions an Italian officer who in 1552, during the war between Henry II of France and Emperor Charles V, was threatened with public execution; he became so agitated that he sweated blood from every portion of the body.