You have a few options to try and avoid a warrant.
1) Of course, the best way is to attend. I understand that financially this may not be possible, but failing to attend can have more costly consequences. A Judge can't be lenient with a person who isn't there. If you do not attend and continue to not be able to pay, you may face difficulties in renewing your car registration, you may lose your drivers license and of course, interest is charged at 6% on any back owed arrearages.
2) You might try seeking the help of a Legal Aid office in Lubbock County. They generally require you to come in person to their offices but they might make an exception for you if you could provide evidence of your medical hardship. Legal Aid might be able to provide you a lawyer at no cost.
3) You could try hiring an attorney in Lubbock County that might take your case on for a reduced or pro bono fee.
Somebody needs to be at that hearing on your behalf if you can't be there. Even if you can't afford to hire an attorney to represent you in court, an attorney might be able to get in touch with the OAG on your behalf and get them to move the court date or allow you to appear by phone. Attorneys usually have an easier time talking to the OAG than a lay person.
You could file to have your child support reduced through the court system, which is really more effective than trying to do it solely through the OAG. It's quite possible that you could file to have the support reduced and have the hearing set at the same time that your current hearing is set.
My suggestion is to look for a lawyer in Lubbock County on Avvo.com that offers a free consultation and talk to them about these issues.
Do not ignore the court date but do everything you can to make sure you are there (in person or by phone) or have some sort of representation there.