My 3 month baby is very stubborn and cries loudly non stop until she gets what she wants immediately

A. It’s not believable because the three month old child doesn’t behave like this because they don’t have a sense of understanding of being stubborn to want something desperately it’s not like that maybe there is some other thing happening because at this age they don’t even have a sense of what is around them what are they having that they will be stubborn about something it could be some other issue please try to figure it out and check with your doctor