Federal law does not require sick leave. If you quit your job before using all of your sick leave, your employer is not obligated to pay you for that time.
The Family and Medical Leave Act (FMLA) provides for up to 12 weeks of unpaid leave for certain medical situations for either the employee or a member of the employee's immediate family; however, in many instances paid leave may be substituted for unpaid FMLA leave.
DOL Web Pages on This Topic
Wage and Hour Division (WHD) Frequently Asked Questions (FAQs)
A section of these FAQs cover medical leave questions.
elaws FMLA Advisor Frequently Asked Questions (FAQs)
FMLA provides for unpaid sick leave. Look here for specific information about FMLA leave.
Coverage Under the Fair Labor Standards Act (FLSA) Fact Sheet
General information about who is covered by the FLSA.