Ive beenon disability for 15 years and live with my childrens mom and children i have no current support order for past 15 years due to my disability

Now child support wants a letter from doctor stating im permantly disabled in order to reveiw the arrears from before i became disabled, my disbility is an emotional and mental one i i suffer from depression, anxiety, anger problems and more as well as i have severe asthma, high blood pressure i have about 4 different meds i take daily for my mental problems, and meds for my blood pressure and heart problems a nbulizer machine for my asthma and inhaler for travel , i recently went back to court for current support and still the judge ruled no current support to my disability and because all my money from my ssi and ssdi check are already figured in the household budget, now they want a letter from doctor saying im permantly disabled the doctor who declared me disabled many years ago passed away , but i still have the same counselor all these years can he write me a statement? i do get disability in the state of ma. my kids mom is the representative payee she handles all my money and appointments for me all of this is causing so much stress on me and my family is there anything i can do i cannot afford a lawyer in massachusetts or the name of any organizations or someone who would be willing to help