Not having seen the movie myself, how do you know He is crying from pain? Could He be exercising His lungs, as all healthy newborns do? My screaming daughters weren't in pain, but they were using their lungs for the first time and therefore crying.
Granted, I interpret the infant Jesus' cry as a cry of discomfort in the film.
But I am curious as to how you "know" that your daughters were not crying in discomfort themselves. The doctors didn't spank them to force them to breathe through their lungs? Have they remembered their births, and told you they were not in pain? Call me a Freudian if you like, but the experience of being violently expelled from the womb is usually presumed to be "traumatic" for the infant.
No need to reply. I ask these things rhetorically.
Jesus did experience pain in His life. That was part of the point of His coming to earth in human form -- to experience what we all experience, including pain. Obviously, the most important point was so that He would pay the price for the salvation of humankind.
Mary was a human being. Blessed, to be sure, but a fallible human being nonetheless. The Bible does not tell us that Mary was infallible, and certainly does not tell us that she did not have a normal relationship with her husband.
The Bible is the only infallible Word of God.