You can get free assistance in the Stockton pro per clinic at the courthouse on the third floor. They will help you with the forms. Even if he has filed, you can file a response with your own requests. Most likely he is asking for a modification in custody and support; if so, you make your requests to include a request for additional support. You must include a new income and expense report (FL150). If your income has dropped below about $1200/month, you can file a fee waiver form.
With your change in income, assuming custody will be relatively the same, your support may increase. The Courts are not eager to make dramatic changes in custody... they generally look at the history when considering any changes. Also, you can turn collection of support over to Child Support Services... they take care of collection.
Depending on the length of your marriage and your judgment, you may be entitled to spousal support. Finally, if you do hire an attorney, you may be able to have the court order attorney fees.
Has your divorce been final? You must immediately go to the courthouse and find a self-help desk to file an Order to Show Cause re: modification of child custody and support. If you have already been served with his motion, you will still need to file a Response immediately. What is his basis for modification of custody? If there has been a status quo order in place for the past 5 years, unless he shows change of circumstances, custody will not be switched. If he did not mention support in the motion, you must file a motion for child support as well. You may also go to the Department of Child Support Services near you, and the District Attorney will file a case for child support for you.
You should immediately go to the courthouse and speak to the Self-Help or Court Facilitator's office. Most courthouses have departments that are set up to help people fill out their paperwork. If you cannot pay the court filing fees, you should inquire about a fee waiver. You mentioned that your ex has filed, so I will assume you have been served with his moving papers. You should pay particular attention to the mediaiton date, the court hearing date and file your written response timely. Good Luck.