No, you do not need a lawyer. Talk to the school's finance office to understand where the problem lies with FAFSA. You can also contact FAFSA to understand the discrepancy.
You may not need a lawyer to talk to them, but a lawyer can certainly help you negotiate a better resolution of the situation. An education lawyer can persuade the school to re characterize the loan, give you more time to pay, and/or obtain other consideration, like a part-time job, etc. Perhaps there is other loan or grant money available, on better terms. exceptions can be made, with some legal pressure.