Is vomitting related to back pain?

Patient: My 8 yr old was injured yesterday on the playground when another kid jumped off of equipment and onto my son’s back , knocked him to the ground as he was running by. He was already dealing with a bad cough, but had not vomitted until tonight. Could the vomiting be related to the injury and if so do I need to take him to the ER or can I make an appt tomorrow?