There is no requirement under Maryland law that would require you to change your business name. However, it is probably prudent to register your business name with the State Department of Assessments and Taxation (SDAT). Here is a link to the SDAT filing form: http://www.dat.state.md.us/sdatweb/nameappl.pdf
Please note that as a sole proprietor, you may not include in the name any language which might imply another form of business (ie, Inc., corp., etc.). Also, as a general matter, you may also want to consider forming a single-member limited liability company (LLC) in lieu of operating as a sole proprietor. Single Member LLCs can offer the liability protection of a corporation without any change in your tax status. An LLC can protect your personal assets from collection on any debts owed to business creditors.
The Kramer Law Firm LLC
3 Bethesda Metro Center
Bethesda, MD 20814