I am sorry to hear this.
It is unlikely that a bus journey can cause it. Your uterus is well padded and protected. Sometimes there are problems with the fetus and it will stop growing and die. This is normally due to genetic problems, or a bad egg or sperm, or the way they combined. Your body will terminate the pregnancy to protect you from harm.
Did your doctor give you something to expell the fetal matter?
Normally an abortion will not affect your ability to get pregnant. But speak to your doctor about it. They have seen what your uterus looks like now.
Take care!