Unless the other party agrees to forgive your arrearages there is nothing that can be done on the back support. You can always file and try to get your current amount lowered, but leaving a job to go into business doesn't usually look good when that business fails. If your income really dropped 80% because of a decision you made that "didn't pan out," why should your child suffer with less support? Be prepared to answer that question. That having been said, if you are making that much less money, the amount you are paying should go down although perhaps not to what your actual income is, since the decrease is your fault. I recommend a consultation with a lawyer to discuss the specific facts in your case.
This answer is provided for general purposes only. If you need legal assistance you should consult with an attorney. If you wish to discuss the facts of your case with me, please feel free to contact my office via the information below. Please note that neither my response to your question nor your contacting of my office creates an attorney-client relationship. Christopher Tamms Tamms Law Office, LLC 6457 Reflections Drive; Dublin, Ohio 43017 Phone- 614-859-9529 email@example.com