You do not have to file if your exemption and standard deduction when added together exceed the income you made. If this is the case you do not need to file, because you would have a zero tax liability. However, if the $7000 is self-employment income you will owe self-employment tax and will need to file. It sounds like that is what this is so you should file.
Any individual seeking legal advice for their own situation should retain their own legal counsel as this response provides information that is general in nature and not specific to any person's unique situation. Circular 230 Disclaimer - Advice given in this response cannot be used to eliminate penalties with the IRS or any other governmental agency.