Child support

I was 15 when I got pregnant. I live in Illinois and my sperm donor (is what I call my sons dad) lives in North Dakota. I am currently not working due to health issues. I need help financially with buying pull-ups and the things my son needs. My sons"dad" used to get him on weekends but has never bought or helped buy anything for him, I was the one always packing bags just for him to go stay the night at his house and he would keep all the items I sent over there with the baby. Since my son is now 2 (be 3 in August) I will need more help with day care and other personal stuff for him! Please help! Any information will be gladly appreciated on this topic.