Single mom/ Lots of medical bills that I need help with - is there any help for me?

the medical bills are piling in and bill collections keep calling. I dont have the money - I really dont. I work full time and try my best but I cannot pay these bills. I recently switched insurance companys because the one I had I guess wasnt paying a big portion of the doctor bills. I was just wondering if anyone knows of any goverment grants or anything else to help get rid of these medical bills. I have bad credit and the only thing is on there is those medical bills. please help. I have a 5 year old son and I want to provide a great life for him but at times I feel stuck because I dont have good credit at all. Any help/advice would be greatly appreciated. thank you.