fundraisers and organizations

ok I am going to run for my sons cause. He doesn't have a dx yet and I don't know when I will get a dx for him, but I will be running for kids with microcephaly. It will be in a couple of months. I ahve to make sure my son kitty kart is in good shape. But my question is that I need to find a organization on where the money will go to. I don't know what to pick. I never done this before. I need some help too. Unless if I do a fundraiser. You know when you don't know what to do? You ahve a child and you don't have a dx for him but the only thing you can do is love them so much? I have done that for 4 years and I feel like I have to go out there to do something for him and for the others like him. Can someone help me out?