When his step-father, Alexander Breckinridge, died in 1801, he was able to return, but had to withdraw again due to a lung illness. He moved to Philadelphia and was placed under the care of Dr. Benjamin Rush, an experience that influenced his decision to pursue a medical career. After an apprenticeship in Louisville, Kentucky, Floyd enrolled in the medical department of the University of Pennsylvania in Philadelphia in 1804 and became an honorary member of the Philadelphia Medical Society and a member of the Philadelphia Medical Lyceum. Floyd was graduated in 1806 and his graduating dissertation was entitled "An Enquiry into the Medical Properties of the Magnolia Tripetala and Magnolia Acuminata". He moved to Lexington, Virginia and then to the town of Christiansburg, Virginia. Floyd also served as a Justice of the Peace in 1807.