My old boy (15) has been having problems chewing recently, thought he may have lost a tooth. Today noticed he has a lump on his bottom jaw, quite firm and painful. His jaw is now quite swollen. Obviously vets tomorrow, he is managing soft pate food, but I'm really worried that it's a tumour. He won't let me look and I don't want to stress him too much. What can I do to make him comfortable in the mean time?