It sounds like you are on probation and a condition of your probation is to pay the court fines and costs. In order to be violated on probation, the violation must be willful and substantial. If you do not have the ability to pay court costs, that cannot sustain a violation unless the prosecutor can prove that you have the means but refuse to pay.
I am a criminal lawyer in Jacksonville, Florida, but probation is similar in any state. I would first go to your probation officer and explain the situation. If nothing happens there, and it probably won't, request to be placed on the judge's calendar to address the issue. Judges like when defendants are proactive and will appreciate you wanting to handle things. The judge can waive your fines altogether or at least make the payment of the fines not part of your probation.
I recommend that you contact a probation/criminal lawyer in Tennessee to discuss your case.
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