TBH it should go off in about 24 hours. You should though still contact the bus comapnty and explain that you have been given whip lash and need to know who there insurance company is to make a claim for time of work etc.
If you need time off work then you will have to be off, the bus comapny insurace will have to pick up the tab tbh it is there responsability - you where on there bus and where their customer to take care of.