Federal labor laws require payment of at least minimum wages for hours worked. Vacation time and sick leave may be another matter. See http://www.dllr.state.md.us/labor/wagepay/wpflexleave.shtml.
You may wish to call an attorney there to discuss the details.
[In accordance with the Avvo community guidelines, this communication does not constitute "legal advice", nor does it form an attorney-client relationship.]