texas infant stroke

my son had a stroke sometime during the first hours of birth however no one will tell me why, test have ruled out anything having to do with his own body causing it but the neurologist will not tell me why it happend no one will i believe it had to do with my delivery because of the report that hospital sent with my son to another hospital that specializes with children. i already talked to a lawyer and explained to him that they say in a report they sent with him that he had oxygen after delivery and he didnt and all the doctors who have seen the mri say it looks like the stroke was due to lack of oxygen but no one will give me a definate time as to when nor why and i dont know how to find out no one will tell me is there anyway someone can help me find out what caused the stroke, cause they know, they just wont tell me, why are they keeping this information from me